英语学习大学物理实验思考

Determination of charge mass ratio of electron by magnetic focusing method
1, the experimental process and sometimes can not find the spot (spot), why?
(1) brightness is not enough. The solution is to appropriately increase the brightness.
(2) has been added with a larger electric bias voltage (x direction or and Y direction), so that the light spot off the oscilloscope screen. At this point, the deflection voltage should be reduced to zero by adjusting the electric deflection knob.
(3) "zero adjustment" knob is used improperly, resulting in the light of the fluorescent screen. By adjusting the "zero", you can find the spot.
2, when the negative to the electric deflection experiment, the external voltage meter pointer will reverse deflection, resulting in the inability to read. Why?
When will the two junction voltage meter end switch, and the measured results of the voltage to the minus sign.
3, after the end of the line, open the "electronic charge mass ratio tester" power, showing the wave tube on what did not appear, why?
(1) "the electronic charge to mass ratio test instrument" on the "gray" knob to adjust too small, the brightness is not enough;
(2) the wave tube has been damaged.
4, after the end of the line, open the "electronic charge mass ratio tester" power, found that there are a lot of bright spots on the oscilloscope, and not in the center of the oscilloscope tube, why?
(1) X plate ungrounded;
(2) switch K1 not hit to ground.
5, "voltage" voltage readings can not pass "at the beginning of the voltage adjustment" or "fine tuning voltage" rotating transferred to the specified value, and why?
(1) "the electronic charge to mass ratio test instrument" on the "gray" knob to adjust too dark or too bright, affects the voltage value;
(2) "the voltage meter" is not adjusted well;
(3) "knob" has been bad;
(4) the voltage meter is bad.
6, switch K1 to the bottom of the wiring column, the wave tube on the line does not appear on the line. Why?
(1) the lower end of the switch K1 wiring column has not received the "electronic charge mass ratio tester", "test power" on the;
(2) the switch K2 has been switched on, and the output of the DC regulated power supply has been adjusted to the measured value, not from the "0".
7, open the "DC regulated power supply" switch, adjust the "output regulation" knob, the wave tube on the graphics did not react, why?
(1) "DC regulated power supply" is short;
(2) "DC regulated power supply" on the fuse has burned off;
(3) "DC regulated power supply" has been bad, there is no voltage output;
(4) the connection between the "DC regulated power supply" and the K2 of the switch is damaged.
Two, the 8 "ampere meter" in series, found that "wiring board" on the "ampere meter" pointer does not move, why?
(1) this "amp" is being reversed;
(2) when the "ampere meter", the "DC regulated power supply";
(3) this "amp" is bad.
Two, the 9 "ampere meter" in series, found that the two meter reading a large difference, and why?
(1) the operator is not facing the dial readings;
(2) one of the table or the two table of the mechanical zero adjustment is not good;
(3) one table or two table is broken.
10, the result of the error is large, why?
(1) the voltage value of the voltage meter deviates from the original value, while the operator does not pay attention to the;
(2) "voltage meter" or "electric current meter" mechanical zero adjustment;
(3) "voltage meter" or "current meter" is bad.
matters needing attention
1 test lines in the use of high pressure, the operation should be careful, in case of electric shock;
2 in order to reduce the interference of other ferromagnetic objects need to be away from the solenoid;
3 should be placed in the South than in the North solenoid;
4 focus points should be as small as possible, but not too bright, so as not to judge the quality of focus;
5 in changing the direction of the current before, should first adjust the exciting current to zero, then the change-over switch Ka, the current is reverse;
6 change the acceleration voltage U, the brightness of the light will change, then need to re adjust the brightness.
If the adjustment of brightness after accelerating voltage changes, voltage adjustment to the desired voltage value.
Michelson Interferometer Experiment
1 observation point light source of the non - Fixed - domain interference, the screen only to see a large spot, can not see the interference fringes, how to do?
Shift walking beam expander, adjust the range of the laser tube, with M1, M2 screw, enable by M1, M2 reflected the bright point can be roughly back to in the laser tube, when the incident light and plate form an angle of 45 degrees. Then re fine-tuning M1, M2 behind the screw, the screen two rows of light spot in the bright point coincide, coincident with the standard is the bright point in pinstripes, other spot also had a pinstriped, put on the beam expanding lens and screen will see interference fringes.
2 observation point light source of the non - Fixed - domain interference, the screen only to see the interference of the arc, not to see the ring, how to do?
Regulate the horizontal tension screw and vertical tension spring screws, so the interference
fringes to thicken thinning are moving in the direction of the, will be transferred out of the interference fringes of the circle.
3 adjust the knob, did not see the ring "coming out" or "indentation", how to do?
Reason: there may be a fine tuning knob and the movable mirror M1 precision screw rod between the emergence of a "slide"".
Way: coarse adjustment handwheel adjustment, the M1 to move to a coarse position, to trim handwheel turn a few laps, ensure fretting drum nut and screw between gapless empty (error), rotational fretting drum, which will see the ring "emerge" or "indent" phenomenon.
Each formal readings before, in order to prevent the deadpath error, should also enable micro drum in multiple rounds, see ring "risk" or "shrink" to go in a direction turns the reading, in the middle of the fretting drum can not be reversed.
4 how to read the M1 position?
The readings from three parts: scale readings, just read out the whole millimeter number can, do not need to estimate; 2, coarse adjusting hand wheel reading directly from the window read mm percentile, also do not need to estimate; 3 fretting drum reading, read out by the micro drum adjacent scale, need to evaluate read a, the readings (Georgia) by 10-4 is several millimeters. M1 position readings for up to three readings and.
5 what is the fixed field interference? What is the non fixed field interference?
The interference fringes are localized or not, depending on the size of the light source. If it is a point light source, the fringe is not fixed, the interference fringes can be seen in the plane mirror M1M2 reflection light wave overlap region. If in the beam expanding lens and light put a frosted glass, point light source emits spherical wave by frosted glass scattering become extended surface light stripes is localized interference (such as inclination fringes).
6 Michelson interferometer compensation board, what is light?
Beam splitter is after the surface is plated with a silver film of semi reflective glass plate, the laser incident after semi reflective film can be decomposed as two beams of strength is approximately equal to the light.
Compensating plate is the refractive index and thickness and beam splitter exactly the same glass plate, so that the beam splitter decomposition of two beams of light meet again in glass plate through the same path, so two beam optical path difference and the glass in the optical path had nothing to do.
7 when the mirror M1 and M2 are not strictly vertical, what are the characteristics of the
distribution of interference fringes observed on the screen?
At this time between M1 and M2 to form a wedge-shaped thin layer of air, with parallel light irradiation will produce such as thickness interference fringes and the air layer thickness is the same point of optical path difference of the same form with a level of interference fringes and the stripes is a series of straight fringe spacing.
8 why can not be directly observed with the eye not to expand the beamLaser beam?
Because there is no expansion of the laser energy concentration, light intensity larger, directly into the eye will cause permanent damage to the retina.
9. In the Michelson interference experiment instrument, laser as light source of the adjustment process, see is two rows of dots or points of light? Why?
The experiment is to see the two row of light, because the light in the glass plate and the plane mirror has multiple reflection. In the experiment, only the most bright spot in the two row of light spot can be adjusted.
In the 10 experiment, why did the experiment data processed by difference method?
In this experiment, we can make full use of the measured data to better estimate the optimal value and estimate the measurement error and uncertainty.
Measurement of moment of inertia of a rigid body
First, how to measure the cycle?
(1) when the chassis in a quiescent state, pad B to rotate a small angle (about 5 degrees), makes a drive along the axis of rotation 50 times, write down the total time period is 50 times the average time.
(2) to measure circle a geometric center axis moment of inertia to the geometric center of the circular shaft remained in the same axis with a.
Two, l, R, R are from where to where the distance?
(1) l is the actual length of the rope connecting the upper and lower two disks (not the vertical length).
(2) R said to tether the distance from the center of the disc.
(3) r point to the center of the disk on the tether distance.
Three, how to measure L, R and R?
Steel tape measure three line pendulum pendulum length L, measured 3 times. L the length must be from the bottom of the pad plate thickness and the center of the chassis thickness center began to measure, because three tether composed of equilateral triangle (guaranteed to be axis), so that the measurement the length of one side of the triangle, to calculate the radius of the radius and the chassis a pad plate B.
Four, how to guarantee the formula and
Established?
(1) before the experiment, we must use the level meter to adjust the A level of the chassis.
(2) to rotate the pad B to start the chassis A rotation, in order to ensure that the chassis A rotation around the shaft.
(3) the angle of rotation of the mat B when it has just turned can not be more than 5 degrees.
(4) three suspension lines must be equal.
Five, how to select the effective number
(1) the last digit of the effective number is one of the absolute errors.
(2) in general, the effective number of errors is only one.
(3) any of the measured results, the final value of the value of a alignment with the error.
(4) to determine the effective number of the absolute error, the reading must be recorded in the assessment of a read.
Holzer effect (Effect Hall)
1, in the process of the wire are connected, the switch is closed, but Vh does not show the number, Im and Is shows the normal, why?
(1) the wires in the Vh group may be in bad contact or have been broken. Carefully check the wire and switch connection and the wire is in good condition.
(2) Vh switch may be poor contact. Repeatedly flipped the switch to see whether the normal.
(3) the possible display of the instrument itself is a problem.
2, Im and Is shows a stable, Vh number is very unstable, and why?
Instrument problem. Replacement instrument.
3, when measuring Hall voltage by using the symmetrical measuring method, change the sign of the Is or Im direction, the Hall voltage value does not change?
(1) may be due to four connections of Hall element connection error of Hall element has burnt out.
(2) may be missed in the terminal wire in the middle, the switch can't change the direction of.
4, after the connection to open the instrument Im or Is number is zero, Vh has shown a number?
(1) the connection between the conductor and the hall element is bad or has been broken, the connection is broken, and the re welding is broken.
(2) two sets of switches may be poor contact.
5, Im or Is number is not stable and the number of Vh is not stable?
(1) the instrument itself is faulty.
(2) to regulate the Im or Is too fast to make the instrument response to failure. Close the instrument, re open the instrument after the slow adjustment of Im or Is.
(3) to adjust the Im or Is knob to poor contact.
6, the result of the error is large?
(1) the Hall voltage and voltage values deviate from the original value, while the operator does not pay attention to.
(2) the long time current is the hall element performance has the influence, causes the error to be big.
(3) the position of the small cursor under the X2 scale of the instrument may be moved, so that the error of the result is too large.
matters needing attention
1 Is maximum value can not exceed 40mA. Im value does not exceed 1mA.
2. Carefully check each connection, it must not be Kati and is connected to the input im output,
otherwise electricity will burn Hall element.
3. In order to reduce the heat flux effect caused by error, measuring curve of Vh--Im measuring Im=1mA TB without equipment cool for a few minutes, and in the process as much as possible reduce long pass current.
Four can not arbitrarily open the hall element of the 4 connection.
Hydrogen atomic spectrum
1 as the field of view is very narrow, the spectral line is very dark, how to deal with?
Nut adjustable eyepiece front, make field width.
2 if the black triangle in the field of view is not clear or simply can not see how to deal with?
Adjustable eyepiece until see so far.
3, such as the field of view of the spectral line tilt, how to deal with?
To fine tune the rotation of the slit so that the spectral line is vertical.
4 if the black triangle is not located in the field of view, how to deal with it?
The rotatable eyepiece ring, the black triangle in the field below.
5 why do not see the spectral line?
May is slit open or slit spacing is too small, may also be drum did not go to the spectrum line or light strays too far from the slit.
6 why weak spectral lines (weak red, Ruo Zi) less than?
May be the first lens did not bring the light together, can adjust the position of the lens 1.
7 Why do hydrogen lamp when the spectral line is relatively dark or weak purple can not find?
It may be that the light is not sufficient, and can adjust the angle between the hydrogen lamp and the slit or the appropriate slit, or move the lamp closer to the slit and the lamp with the slit.
8 why did the hydrogen lamp suddenly come up and see no line?
May be field is not in the visible light region is generally finish after the mercury lamp is not the black triangle moved to the location of the yellow line, look at the position of the yellow line of
mercury lamp, and then the drum turns to the position.
9 Why do when the yellow line on the left there is no red mercury but only a red?
Should be the yellow line has not been separated, need to continue to adjust, until the slit to the focal plane of the lens 3.
Oscilloscope and its application
1 in good condition of the oscilloscope, the fluorescent screen can not see the bright spot, how to find a bright spot? The display of graphics is not clear how to do?
The first highlight knob to the proper position, should not be too large, otherwise damage the screen, it is not the focus. After turning off the scanning signal on the oscilloscope panel (such as the Y x key), the upper and lower displacement keys or the left and right displacement keys are adjusted. Adjust the focus knob, can make the graphics more clearly.
2. If a sinusoidal voltage signal from the y-axis input oscilloscope, fluorescent screen to see a sine wave, but only shows a vertical or horizontal line, it should be how to adjust in order to show the sine wave?
If it is a vertical line, then the test signals are input to check if the X direction. If the Y - x key is popped, or (t/div) whether the scan rate is in use. If it is a horizontal line, then try to check whether the signal input Y direction normal. If (v/div) attenuator is enough to hit a stall.
3 observe the sine wave pattern, how to adjust the waveform when the wave is not stable?
Adjust (t/div) scan rate knob and (variable) sweep?The more so because the comb person rig level Yohe trig level). (source) the trigger source should be adapted to the input of the Y axis, and the amplitude of the Y axis on the screen can not be too small.
4 to observe the pattern of Li Saru, if only to see the processing method of vertical or horizontal line?
Because the Li Saru figure is the sine wave signal of the direction of the oscilloscope y and X direction of the sine wave signal synthesis. So, try to check the adjustment of the CH1 channel (v/div) in the attenuator knob or CH2 channel (v/div) attenuator knob.
5 when measuring the peak to peak value of the signal voltage to be measured with an oscilloscope, how to read from the screen of the oscilloscope accurately?
Before reading the number of grid, should make the "vertical fine-tuning" to CAL. Suggested use under displacement position() knob will sine wave crests or troughs align a transverse lattice and lattice number, not two number lattice appear too large errors.
6 how to use an oscilloscope to measure the time (period)?
Before reading the number of grid, should make the "vertical fine-tuning" to CAL. According to the screen on the X axis scale, read the level (DIV) how much distance between two points in a cycle of the whole story, such as t/div value for 0.5ms/div, then cycle = horizontal distance (DIV) * 0.5ms/div.
7 Lissajous figure instability?
Carefully adjust the frequency of the Y directional signal to make the graphics stable.。