experiment1
中药分析实验1
实验一比色法测定大黄中有效成分的总量学时分配：6学时实验目的和要求1.掌握羧基蒽醌苷类及游离羧基蒽醌的性质；2.通过本次实验了解大黄类药材中有效成分的含量测定方法。
实验原理有色物质的溶液对不同波长的入射光线有不同程度的吸收，这是物质的性质。
溶液颜色的深浅往往是溶液浓度高低的标志，而颜色的深浅与对一定波长的吸收度有关。
因此，可以通过比较溶液对被吸收光的吸收度来测定溶液中物质的含量。
实验条件1.仪器：分光光度计，移液管，容量瓶，锥形瓶，量筒。
2.试剂：NaHCO3, 10%FeCl3, 浓盐酸，氯仿，0.5% 醋酸镁甲醇溶液。
实验内容1.对照品溶液及标准曲线：精密称取1，8 –二羟基蒽醌2.5 mg 于25 ml 容量瓶中，加氯仿溶解并加至刻度，精密吸取对照品溶液0.5，1，2，3，4 ml ，分别置于25 ml 容量瓶中，蒸去氯仿，加0.5% 醋酸镁甲醇溶液至刻度，摇匀。
以甲醇为空白，在515 nm 处测定，以吸收度为纵坐标，浓度(μg / ml)为横坐标，绘制标准曲线。
2.定量分析精密称取药材粉0.1 g ，置100 ml 烧瓶中，精密加入水25 ml ，称定重量。
直火加热15 分钟，放冷，称定重量，用水补足至原重量，加碳酸氢钠50 mg ，摇匀，静置后用干燥滤纸滤过，弃去初滤液，精密吸取续滤液10 ml ，置100 ml 具塞烧瓶中，加10%FeCl3溶液20 ml ，回流20 分钟，加HCl 1ml ，继续回流30 分钟，放冷，加入氯仿25 ml ，盖好瓶盖，用力振摇，转移至125 ml 分液漏斗中，使分层，分取氯仿层，再用20 ml 氯仿（洗涤烧瓶后）萃取一次，分取氯仿层与上次合并，并用水洗涤二次，每次用水15 ml ，将氯仿层用干燥滤纸滤过于50 ml 容量瓶中，用氯仿洗涤滤纸，洗液合并于容量瓶中，用氯仿稀释至刻度，摇匀。
精密吸取5 ml 氯仿提取液，置25 ml 具塞烧瓶中，蒸去氯仿，放冷，精密加入0.5% 醋酸镁甲醇溶液10 ml 。
四川大学英语课程描述 Chemistry Experiment (Ⅰ)-1 化学实验(Ⅰ)-1
Sichuan UniversityP.R.ChinaDepartment of Chemical Experiment CenterChemistry Experiment(Ⅰ)-1Course SyllabusCourse Name Chemistry Experiment(Ⅰ)-1Course No.908007010Department Department ofChemicalExperimentCenterHours18Academiccredit1Course Descriptions Chemistry experiment is not only a basic compulsory course for the engineering undergraduate,but also a part of the engineering chemistry teaching new system which is established by the chemistry education base of engineering basic courses after years of reforming and practicing.With“strengthening the basic skills training,focusing on the comprehensive quality training,and promoting the creative consciousness”as a guiding principle.after reconstituting under the teaching idea of“basic training-advanced experiments-integrated design experiments”.the framework of chemistry is broken and the essence of chemistry experiment is picked.The aim of the course is experimental basic training which covers inorganic chemistry experiment,analytical chemistry experiment,organic chemistry experiment,physical chemistry experiment.After this course,the students can grasp the basic chemistry experimental skills and the use of common instruments and provide an excellent foundation for students to study follow-up experiment courses.Course Materials(Textbooks)Xie Chuan and Lu Houfang,Chemical Experiment,Sichuan University PressISBN9787561435502GradingExperiment100%Instructor InformationHuanli Huang,Senior Engineer,Professor,Department of Chemical Experiment Center,Sichuan UniversityTentative Course ScheduleSichuan UniversityP.R.China Chapter Title Topic1The basic knowledge ofchemistry experiment 1)The importance of chemistry experiment2)Requirements of the chemistry experiment3)Error and significant figures4)Rules of chemical laboratory5)Safety of chemical laboratory6)Common chemical experiments equipment2Basic skills of chemistry experiments 1)Weighing2)Solution preparation and calibration3)Separation and purification4)Heating and cooling5)Organic melting point and boiling point measurement6)Measuring3Basic operation training Experiment1The production of glass laboratory instrumentsExperiment2Preparation and concentration of pH solutionExperiment3DistillationExperiment4Isolation and identification of common cationsExperiment5Isolation and identification of common anionsExperiment6Preparation of deionized water and water quality analysisExperiment7Determination of water chemical oxygen demand(Acidic potassiumpermanganate method)Experiment8Determination of SiO2,Fe2O3,A12O3,CaO and MgO content in cementclinkerExperiment9Determination of the dissociation constant of acetic acid(pH method)Experiment10Determination of stability constants of complexesExperimental11Determination of periodate copper solubility product(electromotiveforce method)Experiment12Sichuan UniversityP.R.ChinaDetermination of the rate of chemical reaction and the reaction order Experiments13Redox reactions and electrochemical4The preparation,separation and analysis ofsubstances Experiment14Preparation and quality identification of ferrous ammonium sulfate Experiment15Preparation of MgSO4.7H2OExperiment16The synthesis of the oxalate-iron(III)potassium,and the determination of ion composition and number of chargeExperiment17Preparation of cyclohexeneExperiment18Preparation of positive bromobutaneExperiment19Preparation of n-Butyl AcetateExperiment20Preparation of ethyl benzoateExperiment21Preparation of AcetanilideExperiment22Preparation of adipic acidExperiment23preparation of Cinnamic acidExperiment24Preparation of benzoin isopropyl etherExperiment25Preparation of benzoin butyl etherExperiment26Preparation of benzyl alcohol and benzoic acidExperiment27Preparation of furan methanol and furan carboxylato5Design and ExploratoryExperiments。
EE332LE1rev3
Experiment-1Bipolar Junction Transistor Characterization Introduction The objectives of this experiment are to observe the operatingcharacteristics of bipolar junction transistors (BJTs). Methods forextracting device parameters for circuit design and simulationpurposes are also presented.Precautions Bipolar junction transistors do not employ a fragile, thin gate oxide like MOSFETs do, and they are thus much more robust againstelectrostatic discharge (ESD) damage. Since all three leads of the BJTare interconnected by internal pn-junctions, small charges can bleedoff through the leakage currents of these junctions, and static chargesare soon dissipated internally. For these reasons, BJTs can usually behandled freely, and are rarely damaged by ESD. This makes themvery pleasant to work with.Procedure 1 BJT base lead and sex identificationSet-Up Locate a type 2N3904 BJT from the parts kit. This should be a three lead device in a small plastic TO-92 package. Turn on a bench DMMand configure it to measure (two wire) resistance. Plug a blacksqueeze-hook test lead into the negative (−) banana jack of the meterand a red squeeze-hook test lead into the positive (+) banana jack ofthe meter. The objective of this procedure will be to determine whichlead of the BJT is the base, and whether the BJT is an npn or pnpdevice using only the ohmmeter function of the DMM. Also locate a1N4148 diode that will be used for reference.Measurement-1 Measure the resistance of the 1N4148 diode with the DMM in both the forward and reverse bias directions. Note that the red lead from the(+) input of the DMM is the one which will have the more positivevoltage for this type of test. Record these readings in your labnotebook, and note these readings as being “typical” for a forward andreverse biased pn-junction. You can then refer to these readings todetermine the polarity of pn-junctions that exist within the BJT.Recall that a BJT has pn-junctions between the base and both theemitter and collector terminals. Use the DMM in its ohmmeter settingto test pairs of leads on the BJT and therefore identify the base lead onthe device. From the polarity which causes the base terminal toconduct, deduce whether the BJT is an npn or pnp device.With the base lead identified, it stands to reason that the remainingleads must be the emitter and collector. A few measurements will nextbe made to examine if these two remaining leads can be distinguishedby DMM measurements. First, use the DMM, again in its ohmmetersetting, to measure the resistance between emitter and collector withthe base terminal open circuited. Try this with both polarities of theDMM leads. Next, use the DMM to measure the resistance betweenemitter and collector with the base now connected to the (−) lead ofthe DMM in addition to the other transistor lead that is already there.Again, try this in both polarity directions. Finally, use the DMM tomeasure the resistance between the emitter and collector with the baseconnected to the (+) lead of the DMM in addition to the othertransistor lead that is already there. Again, try both polarity directions.You should end up with a total of six resistance measurements: 3different base conditions (open, voltage low, voltage high) times 2emitter/collector test voltage polarities.Question-1 From your measurements above, summarize your findings about the given 2N3904 BJT in your notebook. Draw a picture of the devicepackage and label the leads appropriately as E, B, C. (It isconventional to do this with a view of the device looking down on itwith the leads pointing away from you, as if it were soldered into aprinted circuit board. This is usually termed a component-side view,in reference to the component side of the circuit board.) Is it possibleto distinguish the emitter lead from the collector lead using only anohmmeter? Explain why or why not. Look up the data sheet for thethe 2N3904 and compare your deductions with the manufacturer'sspecifications. The base terminal is normally thought of as the“control” terminal for the BJT, as it controls current flow from emitterto collector. With the base lead open circuited, is the BJT a“normally-on” or a “normally-off” device? Explain your answer inreference to the internal pn-junctions of the BJT and how they must bebiased in order for conduction to occur.Comment Many DMMs have a separate function for pn-junction testing. Onsome meters this is an option on the resistance measurements. In thismode, often termed “diode test,” the DMM outputs a constant currentof about 1 mA and it measures the voltage between the two leadswithout computing a resistance. The measured voltage is the turn-onvoltage of the pn-junction for a 1 mA current, if the diode is forwardbiased. If the diode is reverse biased, then the DMM cannot force 1mA of current into the diode and the voltage across the diode rises upto the upper range limit of the DMM, usually about 1.5 to 2.0 Volts.Some meters give an over-range indication in this case. Using thediode function of a DMM is another way to perform the above tests,and it gives more understandable information about the typicaljunction voltages of the BJT.Procedure 2 Measurement of a BJT using a LabVIEW curve tracer Comment The objective of this procedure is to measure and record the current-voltage (I-V) characteristics of a BJT. For this, automatic computer-controlled instrumentation using LabVIEW and a data acquisition(DAQ) card will be used. Automatic measurements such as these arecommonplace in the industrial environment, since they eliminate muchof the possible variations that result from different human operators ofthe instruments. Automatic sequencing of measurements is also muchfaster than what a human could accomplish. This procedure will alsoprovide some more experience with LabVIEW and computer-controlled electronic instrumentation.Set-Up First, insure that the correct DAQ hardware is connected to thecomputer on the lab bench. A National Instruments PCI-6251M DAQcard should be installed with a 68-conductor cable that leads to thework surface of the lab bench. Instead of using the BNC-2120connector block, a simpler CB-68LP or CB-68LPR connector blockwill be used. This should be connected to the 68-conductor cable fromthe DAQ card.The DAQ card only inputs and outputs analog voltages, so to performmeasurements of current, external current sensing resistors must beused. These will be connected directly to the connector block. TheCB-68LP connector block will thus be configured to create the “front-end” of the curve tracer instrument. To set up this front-end, use thefollowing parts:RB = 100 kΩ 5% 1/4WRC = 1.0 kΩ 5% 1/4W3 long and 1 short jumper wires (#22 AWG solid wire)The LabVIEW curve tracer for this experiment is designed to have twoindependent voltage excitation and voltage sensing circuits, one for thebase of the BJT, and the other for the collector. The measurementswill be made with the emitter at a ground potential reference. Analogoutputs AO-0 and AO-1 of the DAQ card are used for the collectorand base voltage excitations, respectively. Analog inputs AI-6 and AI-7 of the DAQ card are used for the collector and base voltagemeasurements, respectively. The current sensing resistors RC and RBand the BJT under test are then connected as shown in Figure E1.1below.Figure E1.1VCCAO-0 (PIN # 22)AO-GND (PIN # 55)VBBAO-1 (PIN # 21)AI-GND (PIN # 56)VCAI-6 (PIN # 25)VBAI-7 (PIN # 57)Construct the curve tracer front end (all parts in Fig. E1.1 except for the BJT under test) on the CB-68LP connector block as follows: Use the short jumper wire to connect between AO-GND (pin # 55) and AI-GND (pin # 56). Also connect a long jumper wire to the AO-GND (pin # 55) terminal. Just use a small flat-blade screwdriver to tighten the wires into the proper connector block terminals. Connect the collector current sensing resistor RC between the AO-0 (pin # 22) output and the AI-6 (pin # 25) input. Also connect one of the long jumper wires to the AI-6 (pin # 25) input. Connect the base current sensing resistor RB between the AO-1 (pin # 21) output and the AI-7 (pin # 57) input. Also connect one of the long jumper wires to the AI-7 (pin # 57) input. The three long jumper wires will become leads out to the transistor under test. Once you have completed this, the curve tracer front end circuit should look like that in Fig. E1.2 below. Since RB and RC will overlap each other, take care to bend their leads so that they do not short together.Figure E1.2Next construct the BJT test fixture as follows: Insert each of the threelong jumper wires from the CB-68LP connector block into threeadjacent holes in a solderless breadboard. Insert the transistor undertest into three holes which connect its Emitter, Base, and Collectorpins to the proper jumper wire test points in the solderless breadboard.In this case, use a Q1 = 2N3904 npn BJT as the transistor under test.When completed, the transistor test fixture should look like that in Fig.E1.3 below. In Fig. E1.3, the green wire is the emitter, the white is thebase, and the red is the collector.Figure E1.3Next the LabVIEW virtual instrument (VI) will be set up. This hasalready been written for this experiment, so all that is needed is to loadit into the computer at the lab bench and launch it. The LabVIEWcurve tracer uses three VIs: TransistorCurveTracer.vi is the main VI,and it uses two sub-VIs, TransistorStepGenerator.vi andTransistorMeasurement.vi. If these do not already exist on the labcomputer, you can download them from the EE-332 class web site.From the Start Menu, launch LabVIEW 7.1 and then open the virtualinstrument named TransistorCurveTracer.vi. This virtual instrument issimilar to the diode curve tracer used in Experiment-0, but it uses twoindependent voltage source outputs and voltage measurement inputs;one for the base and one for the collector. The BJT curve tracer isdesigned to loop the collector sequence of test voltages inside of aloop for the base sequence of test voltages. Thus if the collector wasset to collect 10 points over a specified range and the base was set tocollect 5 points over another specified range, a total of 50 data pointswould be taken, 10 collector points for each base point. It is importantto understand that the collector loop runs inside the base loop and notvice-versa.Click the Run button on the toolbar to start the TransistorCurveTracerVI. From the front panel controls, set up the base step generator toscan from 1.0 V to 3.0 V in 5 points. This will produce steps of 0.5 Veach. Set the base current sampling resistor to a value of 100 kΩ tomatch to the size of the resistor on the front end circuit. Similarly, setup the collector step generator to san from 0.0 V to 10.0 V in 41points, producing 0.25 V per step. Set the collector current samplingresistor to a value of 1.0 kΩ. The total number of points should be205. Finally, set the delay time (time for each measurement point) tobe 5 ms or more. The resulting front panel should appear as shown inFig. E1.4 below.There are also two front panel indicators which show the maximumamount of current that the curve tracer will allow to be used for themeasurements. IBmax is limited by the highest value of VBB and thesize of the base current sampling resistor, IBmax = VBBmax / RB.Similary, ICmax = VCCmax / RC. It is useful to check these valuesbefore starting the measurement sequence to see if they are in therange of what the test device can handle.Figure E1.4Measurement-2 Click on the START SCAN button to start the measurement sequence.The Measuring front panel indicator should turn red in color while theinstrument is taking the measurements. After the measurements havebeen completed (typically a few seconds), the red light should go offand a set of BJT output characterisitics should appear in graph on thefront panel, as shown in Fig. E1.4 above.The front panel I-V graph plots the collector current I C versus thecollector-emitter voltage V CE. Since the emitter is grounded in themeasurements, V C = V CE. All of the measurement points are plotted asone long chain of (x,y) data, so this introduces the four straight retracelines back to the origin where V CC changes from its maximum to itsminimum values as the value of V BB is incremented. Each of the fivemain curves shown on the graph correspond to fixed values of V BB.Since the base-emitter voltage of the BJT is relatively constant, thesefive curves also represent the output characteristics of the BJT forrelatively constant base current, I B. Commercial curve tracers usuallyplot the output characteristics versus stepped values of I B rather thanV BB, so this is the more common way to usually view the data.After you have obtained a reasonable looking set of data as shown onthe front panel graph, click on the SAVE DATA button. A dialogwindow will open in which you can specify the filename and locationfor where the measurements will be stored. The format will be that ofan Excel spreadsheet, so use a filename such as “BJTIVData1.xls”which will have an .xls filename extension. Click on OK, and theWriting front panel indicator will briefly glow red while the file iswritten.Click on the STOP button to halt the execution of the VI. This is doneto free up the computer for faster execution of other functions whilemeasurements are not being made.Question-2 Launch Microsoft Excel and open the new spreadsheet of BJT datathat was just created. The LabVIEW VI will have written six columnsof data into the first worksheet of the file. The columns are, going leftto right: {VBB, VCC, VB, VC, IB, IC}. Each row corresponds to theset of these values for each of the measurement points. There shouldbe 205 rows in the worksheet, corresponding to the 205 measurementpoints. The VBB and VCC values are in units of Volts and are just thevalues created by the base and collector step generators. The VB andVC values are those measured by the two analog input channels, alsoexpressed in units of Volts. IB and IC are the computed base andcollector currents, in units of mA. The LabVIEW VI internally makesthese current calculations so that the I-V data can be displayedimmediately after the measurements are taken. These are computedusing Ohm’s law for the given values of base and collector currentsampling resistors: IB = (VBB – VB) / RB, and IC = (VCC – VC) /RC. If you are interested in how LabVIEW computes these values,you can open the block diagram for the TransistorCurveTracer.vi andsee how this was done.The DC forward current gain of the BJT is denoted by βF and is theratio of the collector to base currents: βF = I C/I B. This is perhaps thesingle most important parameter for characterization of the BJT. βFdepends upon many factors and can be measured at many differentpoints on the characteristic curves. In circuit design βF gets used as aconstant proportionality factor of collector to base current flow, and thus it should be measured at points on the characteristic curves where the collector current is actually proportional to the base current. Examining the characteristic curves which were just recorded, you should observe a region to the right of the saturation knee where the collector current flattens out, becoming nearly independent of V CE, and where the vertical distance between successive base current sweeps is approximately constant. Measuring βF anywhere within this region should yield values which are more or less constant over that whole region. Determine βF for this set of characteristic curves for the 2N3904 BJT by creating a new column in the Excel spreadsheet which divides the IC column by the IB column. You should get a value in the range of 100 to 300 for those points where the value of VC is greater than the saturation knee. From your measured data, suggest a suitable value of common-emitter forward current gain βF that characterizes the 2N3904 BJT.Below the saturation knee, the value of I C/I B will be less than its maximum value of βF, and this is termed the forced-β, or βforced = I C/I B < βF, in the saturation region of operation. Within the saturation region, V CE = V CE,sat, and this will typically be a small voltage in the range of 0.1 to 0.2 Volts. From the Excel spreadsheet, make a plot of V CE,sat versus I C/I B. You will need to include only those data points which fall within the saturation region. One convenient way to do this is to first sort the data into two ranges; those points which correspond to saturated, and those which correspond to forward-active operation of the BJT; and then plot just those points in the saturation region. From your plotted data, suggest a suitable value of saturation voltage V CE,sat that characterizes the 2N3904 BJT.Procedure 3 Dependence of βF on collector current levelThis procedure is a continuation of Procedure 2. The objective is tomeasure the value of βF over a wider range of currents than was donein Procedure 2.Set-Up Set up the NI-PCI-6251M DAQ card, 68-conductor cable, and CB-68LP connector block as in Procedure 2. Wire up the CB-68LPconnector block as described in Procedure 2 to create the curve tracerfront end circuit of Figs. E1.1 and E1.2, using RB = 100 kΩ and RC =1.0 kΩ. Insert a 2N3904 npn BJT into the solderless breadboard andconnect it to the curve tracer front end circuit as shown in Fig. E1.3.Since we are expecting a βF value of around a few hundred, RB isselected to be about one hundred times the size of RC.Launch LabVIEW 7.1 and open the TransistorCurveTracer.vi. Clickon the Run button to start the VI. Set up the base step generator toscan from 1.0 V to 10.0 V in 10 points, giving a step size of 1.0V/step. Set up the collector step generator to scan from 0.0 V to 10.0V in 41 points, giving a step size of 0.25 V/step. Set the delay time to5 ms or greater. These are the same settings as in Procedure 2, exceptthat the base step generator is set up to run up to higher values of basecurrent and thus produce higher collector currents. Measurement-3 Click on the START SCAN button and wait for the VI to complete the measurements and display the resulting I C versus V CE characteristics.The displayed I C current levels should be higher than those measuredpreviously. The NI-PCI-6251M DAQ card has a limitation of onlybeing able to source or sink 10 mA of current. If more current thanthis would be allowed to flow, the DAQ card decreases the voltagefrom the analog output until the current stays within the 10 mA limit.This is known as fold-back current limiting. Thus, it will not bepossible to measure any currents above 10 mA with theTransistorCurveTracer.vi in its present form. At higher base currentlevels, the I C versus V CE characteristic curves may be seen to startshooting up above the 10 mA level. This is simply the fold-backcurrent limiting taking effect, and it is not any type of breakdowneffect in the transistor itself, although breakdown does sometimesshow a somewhat similar behavior.Once a suitable set of I-V curves has been obtained, click on theSAVE DATA button to store these measurements into an Excelspreadsheet.Next, the transistor characteristics at a much reduced current level willbe measured. Since a βF value of around 100-200 is still anticipated,the value of RB should still remain about 100 times the value of RC.However, to measure lower current levels, both RB and RC should bereduced in the same proportion. Change the present values of theseresistors on the curve tracer front end circuit to be RB = 1.0 MΩ (1000kΩ) and RC = 10 kΩ. Change the base step generator to scan from 1.0V to 3.0 V in 5 points, giving 0.5 V/step. Leave the collector stepgenerator at its present setting to scan from 0.0 V to 10.0 V in 41points, giving 0.25 V/step. Click the START SCAN button to beginthe measurement sequence. The recorded data should show currentlevels approximately a factor of 10 less than those before. Click onthe SAVE DATA button to store these measurements in a (different)Excel spreadsheet. Click on the STOP button to halt the VI. Question-3 From the two Excel spreadsheets that were produced, combine themeasurements into one by copying and pasting the data. Because theTransistorCurveTracer.vi will not send sufficient significant figures tothe spreadsheet for small values of IB, both the base and collectorcurrents should be recomputed within the spreadsheet using theformulas IB = (VBB – VB)/RB and IC = (VCC – VC)/RC, noting thatthere were two sets of RB and RC values used to gather the overalldata. Next, compute the value of βF = I C/I B for each measurementpoint and observe the general trend of the data as a function of thecollector current level. Create a plot of βF versus I C for those pointscorresponding to a forward-active operating point of V CE = 5.0 Volts.Comment on the dependence of βF on I C, and from your plot, estimatethe value of I C which yields the maximum value of βF.Comment At low values of collector current, generation-recombination processes in the base-emitter juction produce additional base current which is notassociated with a proportional collector current. Hence, at low currentlevels, the current gain falls. At high values of collector current, seriesresistance and high-level injection phenomenon become importantboth of which cause the current gain to fall off in this region. All BJTshave a designed “sweet spot” where they deliver maximum currentgain. Usually, other operational parameters such as frequencyresponse, power efficiency, and minimum noise production are alsooptimized around this region. It is certainly possible to use a BJToutside of this region of optimal current gain, but one must sufferdegradation in all of these parameters when doing so. Themanufacturer’s data sheets provide very detailed information abouthow all of these parameters vary with collector current level. A littleeffort expended in matching these performance curves to a givendesign will lead to much better circuit performance.Procedure 4 Measurement of BJT reverse characteristicsComment The objectives of this procedure are to measure the I-V outputcharacteristics of a BJT in the reverse-active region of operation.Set-Up Start from the same set up as in Procedure 2: Set up the NI-PCI-6251M DAQ card, 68-conductor cable, and CB-68LP connector blockas in Procedure 2. Wire up the CB-68LP connector block as describedin Procedure 2 to create the curve tracer front end circuit of Figs. E1.1and E1.2, using RB = 100 kΩ and RC = 1.0 kΩ. Insert a 2N3904 npnBJT into the solderless breadboard and connect it to the curve tracerfront end circuit as shown in Fig. E1.3.Now, reverse the BJT in the solderless breadboard so as to swap theemitter and collector leads. The collector lead should now begrounded, and emitter lead should be connected to the VCC/VC point,and the base should remain where it was originally, connected to theVBB/VB point. This can be simply accomplished by just removingthe BJT, rotating it 180 degrees and re-inserting it into the solderlessbreadboard.Launch LabVIEW 7.1 and open the TransistorCurveTracer.vi. Clickon the Run button to start the VI. Set up the base step generator toscan from 1.0 V to 3.0 V in 5 points, giving a step size of 0.5 V/step.Set up the collector step generator to scan from 0.0 V to 10.0 V in 41points, giving a step size of 0.25 V/step. Set the delay time to 5 ms orgreater. These are the same settings as in Procedure 2. Measurement-4 Click on the START SCAN button to begin the measurementsequence. After the measurements are complete, the resulting I-Vcharacteristics will look quite different from those in Procedure 2.First, all five base voltage curves will appear to lie almost on top ofone another, and second, the current will shoot up to a high value at avoltage of about 7-8 Volts. This rapid increase in current is actuallythe base-emitter junction breaking down. Because the base-emitterjunction is more heavily doped than the base-collector junction, it hasa much lower breakdown voltage. (The breakdown voltage for thebase-collector junction is at least 40 V or more for the 2N3904 npnBJT and out of the range of what can be measured using the LabVIEWcurve tracer.) Because of this large rise in current, the current axis isscaled so that the rest of the 5 curves seem to lie on top of one another.Fix this breakdown voltage problem by changing the collector stepgenerator to scan from 0.0 V to 5.0 V in 21 points, giving 0.25 V/step.Click on the START SCAN button again to remeasure the transistor.The current should no longer show the rapid rise at about 7-8 Volts,but the resulting I-V curves should be very noisy appearing and ratherindistinct. This is because the resulting collector current level is verylow and the front end circuit is not producing very much voltage dropacross the collector current sampling resistor RC to compute anaccurate current.Fix this problem by changing RC to a value of 10 kΩ on the front endcircuit. Be sure to also change the value of RC on the curve tracerfront panel. Click on the START SCAN button again to remeasure thetransistor. The resulting I-V curves should be less noisy, but stillrather small in magnitude (much less than 1 mA anywhere). Becausethe βR is so small, the base current will need to be increased toproduce a reasonable set of I-V curves.Fix this problem by changing RB to a value of 10 kΩ on the front endcircuit. Be sure to also change the value of RB on the curve tracerfront panel. Click on the START SCAN button again to remeasure thetransistor. The resulting I-V curves should now appear reasonablynoise-free and significant in magnitude to provide good data.Click on the SAVE DATA button to record the measurement data toan Excel spreadsheet. Choose a new filename so as to not overwriteany existing measurements. Click the STOP button to halt the VI. Question-4 Using the Excel spreadsheet, calculate the value of βR = I E/I B for each of the measurement points. Note that with the transistor reversed inthe solderless breadboard, the recorded value of I C will, in effect, be I E.What is the typical range of values for βR? Does the value of βR varysignificantly with I E?From your results above, discuss in your notebook theinterchangeability of the emitter and collector leads of a BJT. Whilea BJT consists most simply of just two back-to-back pn-junctions,explain why the conduction from collector to emitter has such a largedifference in current gain with different directions of flow.Procedure 5 Measurement of BJT turn-on voltage and ideality factor Comment The turn-on voltage of the base-emitter junction is denoted by V BE,on or Vγ, and is usually approximated as a constant 0.6 to 0.7 Volts forquick circuit analysis. However, this voltage is not really constant,and varies logarithmically with the base current. The measurements ofthis procedure are to determine the parameters for an ideal diodeequation which models the base-emitter junction characteristics.Set-Up Set up the NI-PCI-6251M DAQ card, 68-conductor cable, and CB-68LP connector block as in Procedure 2. Wire up the CB-68LPconnector block as described in Procedure 2 to create the curve tracerfront end circuit of Figs. E1.1 and E1.2, using RB = 100 kΩ and RC =1.0 kΩ. Insert a 2N3904 npn BJT into the solderless breadboard andconnect it to the curve tracer front end circuit as shown in Fig. E1.3.Because we want to measure only the base-emitter junctioncharacteristics, remove the wire from the base of the BJT and short thebase to the collector with a short jumper wire on the solderlessbreadboard.Launch LabVIEW 7.1 and open the TransistorCurveTracer.vi. Clickon the Run button to start the VI. Set up the base step generator toscan from 0.0 V to 0.0 V in 1 point, giving a step size of “NaN” (Not aNumber). This will keep the base step generator output at 0.0 Voltsand it will not scan over any base voltage values. Set up the collectorstep generator to scan from 0.0 V to 10.0 V in 101 points, giving a stepsize of 0.1 V/step. This will sequence the measurement of 101 pairs of(V BE,I C) values. Since the base and emitter are shorted together, bothterminals are driven with the same curve tracer excitation voltage. Setthe delay time to 5 ms or greater.Measurement-5 Click on the START SCAN button and wait for the VI to complete the measurements and display the resulting I C versus V CE characteristics.This should produce a current-voltage characteristic very similar to aregular pn-junction. Click on the SAVE DATA button and record themeasured data in an Excel spreadsheet. Click on the STOP button tohalt the VI.Question-5 Using the Excel spreadsheet, create a new column which is thelogarithm base 10 of the measured collector current. Use the“LOG10” function in Excel to do this, and do this only for thosemeasurement points whose collector current is non-zero. Now create aplot of LOG10(IC) versus VB. This should produce a nearly straightline. The vertical axis is the logarithm of the collector current, relative。
experiment翻译
experiment翻译
experiment
英/ɪkˈsperɪmənt
美/[ɪkˈsperɪmənt]
n.
实验;试验;尝试;实践
vi.
做试验;进行实验;尝试;试用
第三人称单数：experiments
复数：experiments
现在分词：experimenting
过去式：experimented
过去分词：experimented
派生词：
experimenter n.
记忆技巧：ex 出+ peri 通过；尝试+ ment 表结果→不断尝试→实验
双语例句
全部实验试验尝试实践做试验进行实验试用
1.The results of the experiment are not statistically significant.
从统计学的观点看，实验结果意义不明显。
2.The experiment had the reverse effect to what was intended.
实验的结果与原来的意图相反。
3.Many people do not like the idea of experiments on animals.
许多人不赞成在动物身上做试验。
4.The experiments were carried out under simulated examination conditions.
试验是在模拟的情况下进行的。
5.The temperature remained constant while pressure was a variable in the experiment.
做这实验时温度保持不变，但压力可变。
实验一 氨的制取和性质、铵离子的检验教学设计
实验一氨的制取和性质、铵离子的检验教学设计Teaching design of Experiment 1: preparation and properties of ammonia and test of ammo nium ion实验一氨的制取和性质、铵离子的检验教学设计前言：小泰温馨提醒，化学是自然科学的一种，主要在分子、原子层面，研究物质的组成、性质、结构与变化规律，创造新物质。
是一门以实验为基础在原子层次上研究物质的组成、结构、性质、及变化规律的自然科学。
本教案根据化学课程标准的要求和针对教学对象是高中生群体的特点，将教学诸要素有序安排，确定合适的教学方案的设想和计划、并以启迪发展学生智力为根本目的。
便于学习和使用，本文下载后内容可随意修改调整及打印。
[教学目标]1．知识目标（1）巩固实验制取气体的基本操作方法。
（2）熟练喷泉实验、铵离子检验等基本实验的操作方法。
（3）巩固有关化学基础知识。
2．能力和方法目标（1）通过实验室制取氨气实验、喷泉实验等，提高实验基本操作能力。
（2）通过铵离子检验，提高分析推理能力。
3．情感和价值观目标通过本实验提高学习化学的兴趣。
[实验内容和实验要点]本学生共包含喷泉实验、实验室制取氨气和铵离子检验三项，实验中应巩固的知识、实验所涉及的实验技能、实验注意事项等列表如下：实验内容应巩固的知识涉及的实验技能注意事项氨的制取实验室制氨的原理（1）在试管里加热固体混合物的方法（2）密度比空气小，又易溶于水的气体的收集方法（1）装置应不漏气（2）氯化铵和消石灰工混合均匀（3）装反应混合物的试管管口要稍向下倾斜，先使试管均匀受热后，再将火焰固定在盛放固体的部位加热（4）只能用排空气集气法收集氨气，收集氨气的试管要干燥，试管口要用一小团棉花堵住氨的性质（1）物理性质（颜色、状态、气味、溶解性）（2）化学性质（与水、酸等反应）（1）闻气味方法（2）气体的溶解性实验方法（3）使用浓盐酸、浓硫酸、浓硝酸的技能（1）在氨的溶解性实验中，试管里就充满氨（2）氨与酸反应时，三滴不同酸的位置还宜靠得太近铵离子的检验铵离子的检验原理（1）检验铵离子的性质检验氨气时，不要把石蕊试纸碰到试管口或试管内壁，以免跟反应物中的碱相接触教师在学生做实验前，应把以上各要点向学生交待清楚。
国际物理林匹克竞赛试题Experiment 1 and 2 Solution SUMMARY SHEET
SUMMARY SHEETEXPERIMENT 11.FOR WATER AND RED LIGHT AT EXTREME END OF SPECTRUMk = 1 First Order Rainbow θ1 =129.0° 137.0° φ1 = 137.0 ±5.0°k = 2 Second Order Rainbow θ2= 129.0° φ2 = 231.0 ±3.0°k = 5Fifth Order Rainbow θ5= 126.0° φ5 = 486.0 ±4.0°2. LIQUIDS A AND B USING SECOND ORDER RAINBOWS0 1 2 3 4 5500400 300 200 100o k φk Figure E 1.1.Exact theory value0.7 0.81.0Figure E 1.2SUMMARY SHEET EXPERIMENT 2Is the total momentum conserved?YES /NOAccuracy of computer calculation1.00000018.0100≈0.002% 0:1 (RMS velocity = 0.1) Does the system conserve energy?YES/NO (~ ±1%)Equilibrium value of E k *Equilibrium time SD (Average 24 to 180)(see Fig. E 2.1 )= 0.534 ±0.05 ≅(10 to 20 )1.0⨯ Value of S recorded> 20, e.g. 60 Value of α(for SD =60)(see Fig. E2.2 )= 0.503 Accuracy of α= ±0.02For what time number range is graph, obtained using first value of SR , linear? SZ = 18 to 24Gradient of this graph in linear region 0.027 to 0.47 Accuracy of gradient = 0.002Gradient of AVERAGE <R2> in linear region = 0.035Accuracy of this gradient = ± 0.01* delete as appropriateIs the system a liquid/solid? Liquid/Solid*Mean Momentum of the system at requested steps (S)S <VX,1> <VY,1> <PX> <PY>0 0.0000000 0.0000000 0.000000 0.00000040 0.0000010 0.0000016 0.000048 0.00007780 0.0000018 0.0000001 0.000086 0.000005120 0.0000014 0.0000007 0.000067 0.000034160 0.0000016 0.0000010 0.000077 0.000048Energy of the system at requested steps (S)S <VX,2> <VY,2> <KE> = T* <U> <E>= Total Energy 0 0.0173874 0.0142851 0.760140 -4.7502660 -1.614992 0.0162506 0.0131025 0.704474 -4.6666675 -1.628864 0.0124966 0.0089562 0.514867 -4.2873015 -1.628786 0.0077405 0.0039113 0.279643 -3.8053113 -1.62301 12 0.0118740 0.0120959 0.575278 -4.4081878 -1.6288218 0.0099579 0.0075854 0.421039 -4.0940627 -1.62599 24 0.0108577 0.0116978 0.541332 -4.3385782 -1.62796 30 0.0126065 01000340 0.543372 -4.3407997 -1.62703 50 0.0127138 0.0103334 0.553133 -4.3613165 -1.62753 70 0.0088657 0.0158292 0.592678 -4.4388669 -1.62676 90 0.0107740 0.0076446 0.442087 -4.1357699 -1.62580 130 0.0073008 0.0177446 0.601090 -4.4564333 -1.62713 180 0.0097161 0.0096426 0.464609 -4.1773882 -1.62409All values are in reduced units. <KE> is the mean kinetic energy per atom. <U*> is twice the potential energy. <VX,2> and <VY,2> are the mean values of the squares of the X and Y velocity components, as described in the question. Similarly <VX,1> and <VY,1> are the mean values of the velocity components. <PX> and <PY> are the mean momentum per particle.<R z > curves as a function of timeTYPICAL RESULTS : NOTE THE LARGE VARIATIONS IN THE VALUES OF <R 2>Figure E2.210-2<R2>8640 6 12 18 24Time step sFigure E2,3。
trial,experiment,test,try 对比
`test-tube n slender glass tubmical experiments 试管. `test-tube baby baby that is conceived by artificial insemination, or that develops elsewhere than in a mother's body 试管婴儿.
2 [Tn, Tn.pr] ~ sb (on sth) test sb's knowledge or ability (in a particular area) 测验某人（在某方面的知识或能力）: She tested the whole class on irregular verbs. 她对全班学生进行不规则动词测验.
examination of a person's knowledge or ability in a particular area （对人在某方面的知识或能力的）测验, 测试, 考查: give the pupils a test in arithmetic 对小学生进行算术测验 * an I`Q/in`telligence test 智商[智力]测验 * a`driving-test, ie to obtain a driving licence 驾驶执照考试.
牛津高阶英汉双解词典
trial
/ ?tra??l; ˋtra??l/ n
[C, U] examination of evidence in a lawcourt, by a judge and often a jury, to decide if sb accused of a crime is innocent or guilty 审问; 审讯; 审理; 审判: The trial lasted a week. 审讯持续了一个星期. * trial by jury 陪审 * commit sb for trial, ie send sb to prison, for later trial 将某人拘押候审 * The defendant claimed that he had not had a fair trial. 被告声称未获公正审讯. * The case comes to trial/comes up for trial (iewill be tried) next month. 该案将於下月开庭审理.
实验1的英语
实验1的英语Experiment 1Conducting scientific experiments is a fundamental aspect of the scientific method, providing researchers with valuable insights and data to advance our understanding of the natural world. In this essay, I will delve into the details of Experiment 1, discussing its purpose, methodology, results, and implications.The primary objective of Experiment 1 was to investigate the relationship between the temperature of a liquid and its viscosity. Viscosity is a measure of a fluid's resistance to flow, and it plays a critical role in a wide range of industrial and technological applications, from the production of lubricants and adhesives to the design of efficient fluid delivery systems.To carry out this experiment, we utilized a specialized viscometer, a device designed to measure the viscosity of various liquids. The experiment was conducted in a controlled laboratory setting, where the temperature of the liquid could be precisely regulated andmonitored.The experiment began by selecting a liquid sample, in this case, a commonly used motor oil. We then carefully measured the initial temperature of the liquid and recorded the corresponding viscosity reading from the viscometer. Subsequent measurements were taken as the temperature of the liquid was systematically increased in increments, allowing us to observe the changes in viscosity over a range of temperatures.The data collected during the experiment was meticulously recorded and analyzed using statistical software. The results revealed a clear inverse relationship between temperature and viscosity – as the temperature of the liquid increased, its viscosity decreased in a consistent and predictable manner.This finding aligns with the theoretical understanding of fluid dynamics and the underlying principles that govern the behavior of liquids. As the temperature of a liquid rises, the kinetic energy of its individual molecules increases, leading to a reduction in the intermolecular forces that contribute to viscosity. This, in turn, allows the liquid to flow more easily, resulting in a lower viscosity.The implications of this experiment extend beyond the academic realm and have practical applications in various industries.Understanding the relationship between temperature and viscosity is crucial for the design and optimization of equipment and processes that involve the handling and manipulation of liquids.For example, in the automotive industry, the viscosity of engine oil is a critical factor in ensuring efficient lubrication and minimizing wear on engine components. By understanding how the viscosity of motor oil changes with temperature, engineers can develop more effective lubricant formulations and design engine systems that account for these variations, ultimately improving the performance and longevity of vehicles.Similarly, in the chemical processing industry, the viscosity of various fluids, such as solvents, coatings, and adhesives, plays a significant role in their handling and application. By understanding the temperature-viscosity relationship, manufacturers can optimize their production processes, ensuring the desired viscosity characteristics are maintained throughout the various stages of production and transportation.Moreover, the insights gained from this experiment have broader implications for our understanding of the fundamental principles of fluid mechanics and thermodynamics. By investigating the relationship between temperature and viscosity, researchers can contribute to the ongoing development of theoretical models andsimulations that can be applied to a wide range of fluid-based systems and processes.In conclusion, Experiment 1, which focused on the relationship between temperature and viscosity, has provided valuable insights and practical applications across various industries. The meticulous data collection, analysis, and interpretation have demonstrated the importance of scientific experimentation in advancing our understanding of the natural world and driving technological innovation. As we continue to explore the complexities of fluid dynamics, experiments like this will undoubtedly play a crucial role in expanding the boundaries of human knowledge and fostering new breakthroughs in science and engineering.。
1英语阅读材料-答案版
五、完形填空（共12分，每小题1分）It was a cold afternoon. I was training a football team for first-graders. It was the day of our 35 practice.I seated the kids on a long bench on the grass. Any time I was training a new team, I spent a few minutes getting them to 36 one another, each kid saying his name and the names of all the kids sitting to the left.A few minutes later, I decided to put the kids to a test. Alex was chosen to start at the far left end of the bench, go up to each kid, say that kid’s 37 and then shake his right hand.Alex was doing well and he went down the row --- Dylan, Micah, David, and Beau until he reached Ben. He said Ben’s name and reached out his right hand, but Ben just38 there, his right hand 39 in his jacket.“Ben, why don’t you let Alex shake your hand?” I asked. Ben stood up, and said, “But I don’t have the 40 .” He pulled his jacket away from his right shoulder.Ben’s arm ran from his right shoulder but his arm 41 at the elbow (胳膊肘). No forearm, no hand, no fingers!I got shocked (震惊) and couldn’t think of 42 to say, but the little kids were unwilling to hide their curiosity (好奇心).“Look at that,” said Alex.“Hey, what happened to your arm?” another asked. “Does it hurt?”Ben took off his jacket to 43 the kids what they all wanted to see. He explained to them that he had always been that 44 and that there was nothing45 . What he meant was that he wanted to be treated like everybody else.And he was from that day on.From that day on, he was 46 Ben, one of the players on the team.35. A. first B. next C. later D. last36. A. help B. see C. know D. teach37. A. number B. class C. story D. name38. A. sat B. played C. lay D. studied39. A. opened B. raised C. waved D. hidden40. A. finger B. hand C. foot D. leg41. A. met B. pointed C. stopped D. joined42. A. something B. anything C. nothing D. everything43. A. offer B. give C. show D. ask44. A. style B. manner C. way D. nature45. A. common B. special C. magic D. harmful46. A. also B. even C. yet D. just六、阅读理解。
专题15 阅读理解技巧-备战-江苏中考英语一轮复习(牛津译林版)
专题15 阅读理解技巧一、阅读理解细节题一篇文章必须通过许多细节进一步解释和说明主题，体现中心思想。
因此，阅读理解题中多数是针对文章中的细节而设计的，回答此类问题时，首先要认真审题，理解题意，然后根据提示词或线索词，运用查阅的技巧，快速在原文中查找正确的答案。
这些题目的答案大都可以在文章对应的文字部分找到。
解题应从以下几个方面人手：①直接细节题。
题目主要由how和五个wh开头的问题，即：what，who，when，where，why开头的问题，这类题目一般都比较简单，根据提问的具体内容查找，即可得出答案。
①间接细节题。
一般指以释义或换一种方式重新设计的题目。
解题时，首先要看懂题目，找出题目中的词或词组，然后找出文章中的对应部分。
查找要借助于同义词或同义结构。
因为题目中使用的词语或结构与文章中所使用的不同，但意思相同。
解题技巧：1.阅读问题。
2.在文中找出对应的答案句，即定位。
3.（1）、关键信息定位法。
这个主要是细节题，如涉及到数字（日期、时间、价格等），就可以在文章中快速圈出数字，再找出目标数字及相对应的细节作息，还有人物姓名、地点名词等等，其他的还包括一些提示情节发展，或条纲性关键字眼，如First，Next，Finally等等。
4.（2）、同义定位法。
英文中可以用Paraphrase表示。
同义定位就是指问题所用的关键词和文中的不一致，但属于同义性质，同义转换其实是在关键间的基础上拐了个弯易错点：1.没有注意原文与试题之间的相互转换2.没有掌握中心或者主旨，不知道到何处找到自己所需要的事实真题解析AWith the development of science and technology, our daily life is becoming more colorful and more convenient (便利).An Underwater HotelIt looks like a spaceship but it is actually a picture of an underwater hotel. A company plans to build in the sea which is about 18 metres below the surface. The whole building is underwater and you can get to it by swimming and diving.Google GlassGoogle Glass is a pair of glasses with a battery (电池) hidden inside the frame (边框). It can carry out many of the same tasks as smart phones. The glass has a hidden camera and a tiny screen. It is designed to take hands-free photos or videos of anything people are doing.A New Kind of ShirtHate washing clothes? You’re going to love this kind of shirt made by an American clothing company, Wool & Prince. This shirt can be worn for 100 straight days without washing! The Wool & Prince shirt never needs ironing (熨烫).The Digital LibraryCan you imagine walking into a library and finding all books have turned into computers? The first bookless public library is planned to open in San Antonio, Texas. Computers will take the place of books soon.32. The Digital Library tells us something about a library without ______.A. booksB. computersC. bookshelvesD. readers【答案】A【解析】结合小标题The Digital (数字) Library 下第一句Can you imagine walking into a library and finding all books have turned into computers可知，数字化图书馆把所有的书都换成了电脑。
experiment是什么意思,experiment的解释
experiment是什么意思,experiment的解释汉语翻译n. 实验, 试验, 实验仪器vi. 实验, 尝试【化】实验【医】实验词型变化：名词:experimenter动词过去式:experimented 过去分词:experimented 现在分词:experimenting 第三人称单数:experiments词意辨析：trial, experiment, test, try这些名词均有“试验”之意。
trial: 指为观察、研究某事物以区别其真伪、优劣或效果等而进行较长时间的试验或试用过程。
experiment: 多指用科学方法在实验室内进行较系统的操作实验以验证、解释或说明某一理论、定理或某一观点等。
test: 普通用词，含义广，指用科学方法对某物质进行测试以估价其性质或效能等。
try: 普通用词，多用于口语或非正式场合，指试一试。
英语解释：名词 experiment:1.the act of conducting a controlled test or investigation同义词：experimentation2.the testing of an idea同义词：experimentation3.a venture at something new or different动词 experiment:1.to conduct a test or investigation2.try something new, as in order to gain experience同义词：try out例句：1.The teacher gave each of us a piece of filter paper before doing the experiment.做试验前，老师给我们每个人发了一张滤纸。
2.We are doing a chemical experiment.我们正在做化学实验。
Experiment1
Digital Image Processing Course Experiment ReportExperiment TitleStudent’s NameStudent’s IDClassDate handed inInformation Engineering school, NCUTExperiment 1 Basic Image Operation & Image Transformation 1. Objective(1) to know how to manipulate images(2) to be able to implement basic image transformations in Matlab2. Experiment Content(1) Basic Image Operationa. Read the images img_1.tif, img_2.png given in the folder, and show them in one and two figures respectively.(referenced function: imread, imshow, figure, subplot)b. In matlab, observe the images information from the workspace Panelc. Use size, imfinfo,whos,etc functions to obtain image information respectively.d. Add title to the images. (referenced function: title)e. Implement the following codes in the M-file Editorf=imread(‘img_1.tif’) ;imshow(f);set(figure(1),'NumberTitle','off','Name','my first image’)observe the result, and determine the function of set()f. Save img_1.tif to the directory “d:\imagetest”. If the folder does not exist, please create this new folder first. (referenced function: imwrite)(2) Image transformationa (Optional). write a program capable of reducing the number of intensity levels in an image from 256 to L(in integer powers of 2). The desired number of intensity levels needs to be a varialbe input to your program.b. Zooming and Shrinking Images(a) Write a program capable of shrinking(缩放) an image by nearest, bilinear, and bicubic interpolation respectively.(b) Use your program to zoom the images in (a) back to original size. Explain the resons for their differences.c. Write a program capable of performing the four arithmetic operations between two images. In addition to multiplying two images, your multiplication function must be able to handle multiplication of an image by a constant.Experiment Report RequirementsPage 1. Cover page as illustratedPage 2. Technical discussions.This section should include the techniques used and the principal equations (if any) implemented.本小节包括使用的技术，实现程序使用的主要公式等。
Experiment One(英文版实验一__机构运动简图的测绘和结构分析)
Experiment One: Drawing of Kinematic Diagram of Mechanismand Structural AnalysisI. Aims1. To learn the principles and methods of drawing a schematic diagram of themechanism in terms of the mechanical structure or model structure.2. To verify the calculation of degree of freedom (DOF) or mobility of themechanism and conditions for a mechanism to have a determined motion.II. Experimental device and tools1. Machinery and mechanical models (Automatic punch model, etc.);2. Caliper, steel tap or ruler;3. Set square, compass, pencil and eraser (students should bring along their own). III. Principles of the experimentThe kinematic diagram of the mechanism is simple but can be used to analyze kinematics and dynamics of an existing mechanism or design a new mechanism in the early stages of design. Since this diagram is used only to express the relationship between the motions of links , those detailed structures irrelevant to the motion transmission should be omitted or simplified. Such a diagram is also called the schematic diagram of the mechanism. It provides all necessary information to determine the relative motion of all links. The kinematic function of a link is to hold the relative position of all pair elements on the link unchanged during the motion of the mechanism. In the schematic diagram , links and kinematic pairs are represented by simple and specified symbols as shown in the table 1. In addition, the kinematic characteristics of the mechanism are reflected in the kinematic diagram using the relative motion of all links drawn to scale.IV. Experimental methods and procedures1. Turn or move the mechanism slowly, and study carefully the movement ofthe mechanism starting with the driving link to identify the fixed pair elements, driver and driven link According to the route of motion transmission, the contact form and relativeness between the two interconnected links are analyzed, so then all links of the mechanism, number and types of kinematic pairs are ensured.2. Choose rational projection plane. In general, all moving links of a planarmechanism move in parallel planes. The plane with most links should be chosen as the projection plane.3. Draw the schematic diagram of the mechanism. A location of driving linkcan be chosen arbitrarily, and relative location of each kinematic pairs is set roughly. All links and kinematic pair are drawn using specific symbols shown in Table 1. For convenient reference , the links are numbered while the kinematicpairs are lettered. For example, the corresponding link and kinematic pair are labeled as number 1,2,3 and letter A,B,C respectively. Arrow is used to show driving links’ direction of motion. Noted that the formal schematic diagram of the mechanism should be drawn in proportion to draft drawings of the mechanism.4. Measure accurately the relative location of each kinematic pairs ( e.g., thecenter distance between two turning pairs, the included angle between two guide ways of sliding pairs). Only kinematic dimensions are measured.A suitable scale μis chosen and a schematic diagram of the mechanism are drawn to the scale.Use μto stand for the scale of length of schematic diagram of the mechanism.5. Calculate the degree of freedom or mobility of the mechanism according tothe schematic diagram, and check if it is the same as that of the actual mechanism. V. Questions:1. What can be shown in a schematic diagram of the mechanism?2. What is helpful for drawing a schematic diagram of the mechanism to do thecalculation of degree of freedom (DOF) or mobility of the mechanism?3. Any suggestions and comments?Table 1 Special Symbols for Some Commonly Used Mechanisms。
Experiment1 Liquid Dosage Forms_工业药剂学
Experiment 1 Liquid Dosage FormsLiquid dosage forms are preparations containing medicaments dissolved in a suitable solvent. It is the basal dosage form for some ordinary preparations such as injection, ointment, suppository, aerosol and so on.Depending on the dispersing system, liquid formulation is classified into homogeneous and heterogeneous liquid dosage forms. The homogeneous liquid dosage forms include solutions and macromolecular solutions, while sols, suspensions and emulsions are heterogeneous liquid dosage forms.Part 1 SolutionsPurpose1. To master the basic methods of solution preparation.2.To master the operation technical of supplemental agent in solution.IntroductionSolution preparations are liquid preparations containing medicaments dissolved in a suitable solvent to form a solution. They are usually prepared by the technical of solution, dilution and chemical reaction method. Water, alcohol, glycerol and propylene glycol are the most frequently used solvents.Solution preparations include solutions, aromatic waters, syrups, etc. while solutions (liquid preparations containing soluble medicaments dissolved in a suitable solvent to form a clear solution) and syrups (concentrated aqueous solutions of sucrose containing extracts of crude drugs or aromatic materials) are more commonly used.To prepare a solution of a water-insoluble drug, the most important respect is the approaches to improvement of aqueous solubility. The feasible methods include:Particle size control The size and shape of very small particles, if less than 1μm diameter, can affect their solubility. Solubility will increase as the decreasing of particle size.pH control A large number of drugs are weak acid or weak bases, therefore their solubility in water can be influenced by the pH of the systems, just as the solubility of a weak acid is improved by an increase in pH.Solubilization The solubility of a drug that is normally insoluble or poorly soluble in water can often be improved by the addition of surface-active agent. These molecules form different types of micelles, ranging from simple spherical structures to more complex liposomes and liquid crystals. The surfactant chosen must be non-toxic and non-irritant, bearing in mind its intended route of administration.Cosolvency The solubility of a weak electrolyte or non-polar compound in water can often be improved by altering the polarity of the solvent. This can be achieved by the addition of another solvent that is miscible with water and in which the compound is also soluble. Vehicles used in combination to increase the solubility of a drug are called cosolvents, and often the solubility in this mixed system is greater than that can be predicted from the material’s solubility in each individual solvent.Complexation In some cases, it may be possible to interact a poorly soluble drug with a soluble material to form a soluble intermolecular complex, such as the interaction of salicylates and benzoates with xanthines.Chemical modification As a last resort, chemical modification of a drug may be used in order to produce a water-soluble derivative.Besides the solvents (water, alcohols, etc.), several kinds of additives may be incorporated into the solutions to improve the formulation characteristics and stability, such as the solubility enhancing agents, sweetening agents, viscosity enhancing agents, isotonic modifiers, antioxidants, flavors and colors. The technical of pulverization can be applied to accelerate the process of drug dissolution. 1/2～3/4 of the solvent is added firstly while stirring, heat if necessary if the drug is not heat-sensitive.Equipments and Materials1. Equipmentsbeaker (50ml), glass filter (6cm, 10cm), measuring cylinder (100ml), balance, glass stick, filter paper, electric furnace2. Materialsiodine, potassium iodide, sucrose, chloramphenicol, ethanol, distilled waterProcedures1. Compound IodideIodine 2.5gPotassium iodide 5gDistilled water add to 50mlPlace potassium iodide and 50% to 80% water into the beaker and dissolve it by stirring. Add iodine to the solution and stir to make it dissolve completely. Then add the remaining water and mix.2. Simple syrupSucrose 85gDistilled water add to 100mlSucrose was dissolved with 45ml of distilled water. The solution was then filtered through refined cotton immediately after boiling. Finally, add the remaining water to the filtered solutionthrough the colander and mix.3. chloramphenicol eardropsChloramphenicol 2.5gEthanol 15mlGlycerol add to 50mlAdd chloramphenicol into ethanol and stir until it was dissolved completely. Then add glycerol to 50ml volume, mix and filter.Experimental InstructionsRequirements for preview1. To master the methods to improve the solubility of drugs.2. To be familiar with the solvent using in solution.3. To point out the procedures and precautions according the experimental teaching material.Procedures and Precautions1. The solubility of iodine in water is 1:2950，potassium iodide may effectively enhance the solubility of iodine by interacting with iodine to form a soluble complex. Meanwhile, it may also reduce the volatility and irritation of iodine.2. When preparing compound iodine solution, order of the material adding should be noticed.3. The volume of water to dissolve potassium iodide should better be 50% to 80% of the whole volume, which may dissolve potassium iodide rapidly and keep the higher concentration of potassium iodide beneficial to the dissolution of iodine.4. Compound iodine solution should be preserved in airtight glass bottle without any contact with cork, rubber or metal stopper due to its oxidation character.5. In the preparation process of simple syrup, the sucrose solution should be kept in boiling state after dissolving completely, but the boiling time should not be too long to prevent the transformation of sucrose, otherwise the syrup may turned into brown.6. The filtration of syrup can be speed up by using cotton cushions or multiplayer gauzes.7. The simple syrup should be filtrated immediately after boiling. Otherwise, the process will be difficult as its high viscosity.8. The solubility of chloramphenicol in water is lower than 0.25%. however, it is easily soluble in ethanol. So the addition of ethanol can increase the solubility of chloramphenicol and prevent the precipitation of chloramphenicol solution in low temperature.Questions1. What are the functions of the various constituents in formulations in this experiment?2. What should be noticed in the preparation of simple syrup? What effective steps can beadopted?3. The drug should be dissolved, and then diluted when prepare the solution of a water-insoluble drug, why this preparation technical is applied?Part 2 Colloidal solutionsPurpose1. To be familiar with the types and characteristics of colloidal solution.2. To master the experimental process and related proceedings, according to the experimental teaching materials.IntroductionA colloidal solution is a homogeneous or heterogeneous liquid system with 1～100nm solid particles. Some colloidal materials, such as pepsin, trypsin, cellulose derivatives, can form hydrophilic colloidal solution when contact with water.According to their affinity with dispersing agents and rheology characteristics, colloidal material may be classified into two groups: hydrophilic colloid and hydrophobic colloid. The types of colloidal solutions include hydrophilic colloidal solution, hydrophobic colloidal solution, protective colloidal solution, thixotrope and gel.The preparation of colloidal solutions is similar with hypomolecular solutions, but the drug should be swelled first, and then dissolved by stirring or heat.Equipment and Materials1.Equipmentsbeaker, glass stick, balance, graduated cylinder.2.Materialspepsin, hydrochloric acid solution, glycerol, distilled water.ProceduresPepsin mixturesPepsin (1:3000) 3gDiluted hydrochloric acid 2mlGlycerol 20mlDistilled water add to 100mlAdd 70% of water, diluted HCl, glycerol into the container and mix. After that, pepsin wasscattered on the surface of the mixed liquid and swollen naturally, then stir gently to dissolve pepsin. Finally, add the remaining water and mix.Experimental InstructionsRequirements for preview1. To master the category and characteristics of the colloidal solution.2. To point out the procedures and precautions according the experimental material.Procedures and Precautions1. The weighing process should be quick in high humidity conditions because pepsin can adsorb moisture easily.2. Pepsin can keep its best activity at pH 1.5～2.0, however, more than 0.5% HCl may destroy its activity. Direct mixing of pepsin with HCl was not allowed for the stability concerned.3. 20% of glycerol may adjust the taste of this preparation and maintain the stability of pepsin.4. Vigorous stirring and filter with cotton or filter paper may impact the activity and stability of pepsin.Question1. What are the functions various constituents in formulation in this experiment?2. Describe the process of swelling and peptization of the hydrophilic colloid.Part 3 SuspensionsPurpose1. To master the general preparation methods of suspensions.2. To be familiar with the use of suspending agent, flocculating agent and wetting agent in suspensions.3. To understand the evaluation method of suspensions.IntroductionSuspensions are liquid preparations containing insoluble solid medicaments dispersed in a liquid dispersing medium. Suspensions are used in pharmacy in many different dosage forms and can be taken orally, applied topically or injected. One of the main criteria for an optimum formulation of suspensions is that, after shaking, the disperse phase should be uniformly distributed and suspended in order to ensure the administration of a uniform dose. The rate of sedimentation of the suspended phase depends on several factors and can be approximated to2122()9r grate ρρη-=We can theoretically decrease the settling rate by, -Decreasing the particle size(r)-Increasing the viscosity of the disperse phase(η)-Decreasing the difference between the density of the particle(ρ1)the disperse phase(ρ2). Obviously, increasing settling can be achieved by increasing the gravitational forces (g) as occurs in centrifugation.Thus, decreasing particle size and suspending the particles in a more dense and viscous liquid are ways by which settling may be reduced. However, reducing particle size may affect the bioavailability of the formulation and lead to unstable systems. Therefore the main way in pharmacy to decrease sedimentation is to employ suspending agents.Stabilizers usually used in suspension include, - Suspending agent - Wetting agent- Flocculating agent or deflocculating agentThe preparation methods of suspension include dispersing method, (such as grinding)and coacervation method （such as micro-particle crystallization and chemical reaction ）.Equipments and Materials1. Equipmentsmortar and pestle, beaker, measuring cylinder, balance. 2. Materialscalamine, zinc oxide, glycerol, sodium citrate, aluminum chloride, CMC-Na, sedimentation sulphur, benzalkonium bromide, zinc sulfate, camphor spirits, sulfadiazine, sodium hydroxide, citric acid, sodium citrate, sodium benzoate, sodium saccharin, flavor, distilled waterProcedures1. Calamine lotionsFive kinds of samples were prepared according to the following table.Tab 1-1 Composition of five groups of calamine lotionsCalamine lotions were prepared by grinding method while adding liquid.Calamine and zinc oxide were placed in the pestle. glycerol was added and ground homogeneously to get a paste. Other ingredients were added and ground homogeneous too. Finally, the remaining water was added and ground to get the final suspensions.CMC–Na must be swollen with a little water before adding into the mixture.2. Determination of sedimentation volume (F) of calamine lotionsPlace five kinds of lotions into five 50ml measuring cylinders with stopper respectively. Stopper the measuring cylinders and shake for 1min. Each original height H0 was written down. After specified intervals, the heights of sedimentation H u were recorded into Tab 1-2.Sedimentation curve was plotted, F（F＝H u/H0）as the ordinate and time t as the abscissa.Tab 1-2 Sedimentation data recordedSedimentation sulphur 1.5gZinc sulfate 1.5gTween 80 0.1mlCamphor spirits 12.5mlGlycerol 2mlDistilled water add to 50mlPlace sulphur and glycerol in the mortar and triturate. Dissolve zinc sulfate in about 10ml of water and add slowly into the mortar. Slowly add camphor spirits while triturating. Finally, add the remaining water and triturate.Transfer the lotions into measuring cylinder and observe the suspending characteristics.4. Sulfadiazine mixturesSulfadiazine 10gSodium hydroxide 1.6gCitric acid 3gSodium citrate 6.5gSodium benzoate 0.2g1% Sodium saccharin Q.SFlavor Q.SDistilled water add to 100mlThe lotions were prepared by micro-crystallization method.Dissolve sodium hydroxide in re-cooled distilled water. Add sulfadiazine and stir continuously to dissolve it completely. Cool the solution to get yellow solution A.Dissolve citric acid in 10ml of water, and then get solution B.Dissolve and mix sodium citrate, sodium benzoate and 1% sodium saccharin in about 30ml of water and stir, then get solution C.Add solution A and solution B (3:1) alternately into solution C. After that, stir for several minutes to make sulfadiazine suspend in water in a micro-crystallization state. Finally, add the remaining water and mix.Experimental InstructionsRequirements for preview1. To master the physical factors, which influence the stability of suspensions.2. To be familiar with the category, function of stabilizer in suspensions.3. To point out the procedures and precautions according the experimental teaching material.Procedures and Precautions1. In calamine lotions, CMC-Na serves as a suspending agent to keep the suspending state of solid drug particle. Addition of aluminum chloride alone or combination with benzalkonium bromide may control the flocculation, while sodium citrate may serve as a deflocculating agent. Aluminum chloride may partly neutralize the negative charge of calamine and zinc oxide to form the loose flocculation products that can prevent agglomeration and provide redispersibility.2. Cogrinding of calamine, zinc oxide with glycerol into paste may make the fine particles of two hydrophilic drugs separately and can disperse into water easily. When shaken, they tend to suspend in liquid.3. Calamine and zinc oxide show negative charge, and can be flocculated by adding a small amount of aluminium trichloride, so that the Calamine lotion can be more stable.4. Among the three kinds of sulphur (sublimation sulphur, refined sulphur and sedimentation sulphur), the particle size of sedimentation sulphur is the smallest. That is why it was chosen as the material to prepare the lotions.5. As a hydrophobic substance, sulphur cannot be wetted easily by water and its surface adsorbs lots of air. So it is difficult for us to prepare its suspensions. However, it can be wetted by appropriate addition of glycerol. So glycerol was added to serve as a wetting agent and adsorbed on the surface of particles to increase the hydrophilicity.6. Addition of camphor spirits into the system should be as slow as streamlet to prevent the separation of camphor because of the sudden solvent change. Meanwhile, rapidly mixing is needed.7. Sulfadiazine is not soluble in water but soluble in alkaline. However, its sodium salt can absorb carbon dioxide and separate out. Color change may also occur in sodium salt because of the oxidation by light and metal ion. So its sodium salt cannot be used to prepare solutions8. Addition of acid into the solution of sodium salt of sulfanilamide can re-precipitate sulfanilamide as a micro-crystallization state at an appropriate pH. This kind of micro-crystallization which the particle is less than 10μm may be used to prepare suspensions, which can be uniformly dispersed and sedimentated slowly. This technology overcomes the shortcomings of sulfanilamide suspension prepared by dispersing method, such as delamination, adhering to container, bad redispersibility and poor absorption.Questions1. What are the functions of various constituents in formulation in this experiment?2. How to judge the quality of Calamine lotion according to the experimental results?3.What kind of drugs can be used with the method of chemical reaction to prepare micro-crystallization, just take one or two drugs as examples? Are there other methods can prepare the micro-crystallization.Part 4 EmulsionsPurpose1. To master the preparation method of emulsions.2. To master the identification method of emulsions.3. To master the method of detecting HLB value.IntroductionEmulsions may be defined as two immiscible liquids, one of which is finely subdivided and uniformly distributed as droplets throughout the other. Emulsions constitute a significant group of pharmaceuticals. Besides those intend for oral administration and intravenous feeding, e.g. lipid emulsions, a large number of external preparations such as creams, ointments, liniments and lotions might be emulsion.Emulsions are unstable thermodynamic systems and normally stabilized by the presence of emulsifying agents. The emulsifying agents are usually chosen according to the type of emulsions, its emulsibility and the route of administration. Appropriate mixing emulsifiers usually exhibit better emulsibility than single. Despite the use of emulsifiers, emulsions may still show a lack of stability in various forms, the most common being creaming, phase inversion and cracking.Methods for emulsion preparation include emulsifier in oil method, emulsifier in water method, nascent soap method and alternate addition method. It can be prepared with theequipment of mortar for a small quantity, while mixer, emulsor and colloid mill are the mostly frequently equipments for large-scale production.Equipments and Materials1. Equipmentsmortar and pestle, measuring cylinder with stopper, microscope, balance2. Materialsliquid paraffin, calcium hydroxide, peanut oil, acacia, tragacanth, tween 80, span 80, distilled waterProcedures1. Lime linimentsCalcium hydroxide solution 10mlPeanut oil 10mlCombine calcium hydroxide solution and peanut oil in the bottle, shake for several minutes until the emulsion is formed.2. Liquid paraffin emulsionsLiquid paraffin 12mlAcacia 4gTragacanth 0.5g5% Ethylparaben alcohol solution 0.1ml1% Sodium saccharin Q.SFlavor Q.SDistilled water ad. 30mlThis formulation was prepared by emulsifier-in-oil method.Combine acacia and tragacanth in a dry mortar and mix, then add liquid paraffin and triturate until the two gums dispersed completely. Add 8ml of water and triturate continuously until the formation of dense primary emulsion. Add another 5ml of water and grind, after that, add ethylparaben alcohol solution, sodium saccharin and flavor with constant triturating until the emulsion is formed.3. Determination of the emulsion typeDetermination of emulsion type was based on the physical characteristics of external phase and internal phase.(1) Dilution methodAdd one drop of liquid paraffin emulsions into test tube containing 5ml of water and shake several times. Record the mixing results. Repeat this procedure using lime liniments.(2) Microscope determinationMake a smear of liquid paraffin emulsions on a slide and dye with Sudan red solutions (oil-soluble dye) and then examine it microscopically. Repeat this procedure with methylene bluesolutions (water-soluble dye).Repeat the above procedure using the lime liniments.4. Determination of required HLB to emulsify liquid paraffinTab 1-3 Composition of five groups of liquid paraffin emulsionsTween80Span80Combine liquid paraffin, tween 80 and span 80 in a dry mortar and mix. Triturate constantly while adding water. After finishing water addition, triturate another 5 minutes.Transfer emulsions into measuring cylinders and record the height of water layer at time of 5, 10, 15 and 45 min.Tab 1-4 Data recorded for the stability of liquid paraffin emulsionsExperimental InstructionsRequirements for preview1. To be familiar with the emulsifying agent commonly used.2. To understand the emulsifier in oil method, emulsifier in water method and nascent soap method.3. To point out the procedures and precautions according the experimental material.Procedures and Precautions1. The W/O type of lime liniment was made by nascent soap method. The emulsifier in the formulation is a nascent calcium soap generated from reaction between calcium hydroxide solution and free fatty acid in peanut oil. Other vegetable oil, such as rape oil and benne oil also contain small amount of free fatty acid, so the peanut oil in the formulation can be replaced by them.2. In preparing this O/W type of liquid paraffin emulsion, inadequate water or too low adding speed may result in W/O primary emulsion and emulsion cracking. If primary emulsions containtoo much water, the viscosity in external phase may be reduced so much that oil phase cannot be dispersed well, and the resulting emulsions may be not stable too. So the quantity of water added should be well controlled.3. When determine of appropriate HLB value to emulsify liquid paraffin, we should combine two emulsifiers at different ratios to get mixing emulsifiers with a range of HLB value and prepare a series of emulsions. Then the best appropriate HLB value to emulsify liquid paraffin can be obtained by determining the creaming rate of those emulsions at ambient temperature or accelerated experiments.Questions1. What are the functions of various ingredients in each formulation of this experiment?2. Which ingredient in each formulation act as the emulsifying agents?3. Analysis the causes which lead to the instability of emulsion as well as its type.。
Experiment_1
Circuit 2 MultiSim Simulation results (Error= output with load – output without load) 10% 20% 30% 40% 50% 60% 70% 80% 90% 10K With buffer Error
Use the measurement result of Experiment 1a
Experiment 1a.
Rp Vs 10 V 50% 10kΩ Key=A
Vo
RL 10kΩ
Circuit 1 MultiSim Simulation results (Error= output with load – output without load) 10% 20% 30% 40% 50% 60% 70% 80% 90% No load 10K Error
Experimental components: One 10kΩ potentiometer DC power supplier (10V) One Multi-meter Three load resistors, 4.7kΩ, 10kΩ and 100kΩ
Requirement: 1. 2. 3. 4. 5. 6. Fill the table with simulated values and determined the non-linearity error. Fill the table with your measured values Calculate the non-linearity error. Draw the I-O characteristics of circuit 1 (with RL and without RL). Indicate the maximum non-linearity error on the I-O characteristics. Conclusion on loading effect.
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
实验一 电位、电压的测量和叠加定理的研究
一、实验目的
1．熟悉实验台的整体布置及交、直流电源和交、直流仪表的使用。
2．学会测量电路中各点的电位和电压的方法。
3．掌握线性电路的叠加定理。
二、实验设备
实验箱（EEL-51）(EEL-53)、恒压源、直流电压表、直流电流表 三、实验内容
1．熟悉实验台的整体布局、记录实验台的主要设备和仪表的参数。
要求记录：设备的名称、规格、量程及精度。
2．熟悉直流恒压源、恒流源和直流电压表、电流表的使用。
(a)自行设计一个电路，以某点为参考点，测量电路各点的电位和两点之间的电压。
具体要求：
①用三个电阻和一个电源（电压不超过8V ）组成一个简单电路； ②由附录中实验箱选择电阻元件的阻值，并画出电路； ③选择参考点计算各点的电位和两点之间的电压，自行设计一个表格，将所计算的数据填入表格中。
然后实际连接电路，测量电位和电压。
(b)叠加定理的研究
使用EEL-53实验箱，按叠加原理图1-1进行实验，测量每个电源（V
U S 121
=，V
U
S 62
=）
单独作用时和共同作用时各支路电流值，填入表1-1中。
表1-1
图1-1 4 5
四、实验注意事项
1．测量直流电压应并联在被测元件上，注意正负极性。
测量直流电流时应串联在被测支路中，要注意电流的方向。
2．选择测量仪表的量程，根据估算选择稍大的量程，如电流偏小，再降低量程，以保证测量的精度。
注意测量仪表报警铃响时，应关闭仪表的电源，检查原因，改正后重新合上仪表的电源。
3．正确使用可调直流恒压源和恒流源，正确读数（读数以电压表测量为准，而不以电源表盘指示值为准）。
4．使用电流插头测量时应注意仪表的极性的正确连接，以及读数时"",""-+号的记录。
5．叠加定理实验中，每个电源单独作用时，去掉另一个电源，是由开关S 1 ，S 2 操作完成，而不能将直流电源短路。
五、预习思考题
1．叠加定理实验中1
S U
，2
S U
分别单独作用时实验中应如何操作？
2．如将叠加定理中电阻R 3改为二极管D 时，叠加定理是否成立？
3．电路中各点电位与选择的参考点有什么关系？任意两点之间的电压与参考点的选择有关系吗？
六、实验报告要求
1．预习报告内容的要求：实验目的、实验设备（写出具体实验箱的型号和测量仪表的型号）、实验内容及步骤、根据实验内容，具体画出线路及实验参数，计算结果，以及设计出测量用的记录表格。
2．总结报告内容的要求：除预习报告内容之外，再增加数据的误差分析或曲线比较，理论分析，故障分析和心得体会。