磁场及磁场对通电导线的作用力PPT教学课件

方程求解
新课标北师大版课件系列
《高中英语》
必修2
the National Treasure
Beijing Opera
Beijing Opera dates back to the 18th century.
It is a combination of acting, talking, singing, music, dancing and acrobatics.
the clothes worn in plays or films
to have a history of
a group of valuable things,very special or important for the country
movement of one’s body using the skills of an acrobatch the main roles with their names. sheng male roles dan female roles jing male roles with brightly painted faces chou clown roles
2. What skills do Beijing Opera actors need to have? It is a combination of acting, talking, singing,
music, dancing and acrobatics. 3. How many main roles are there in Beijing Opera?
It was performed mostly on open-air stages in markets, streets, teahouses or temple courtyards.
2. Why does it have very loud music and a piercing singing style?
sheng male roles with brightly painted faces dan female roles jing clown roles chou male roles
1. When did Beijing Opera start? It dates back to the late 18th century.
a very high and loud voice
Task 1:
Listen to an interview about Beijing Opera and answer the following questions.
1. When did Beijing Opera start? 2. What skills do Beijing Opera actors need to have? 3. How many main roles are there in Beijing Opera? 4. Match the main roles with their names.
The costumes are always in bright colour.
costume
date back combination a national treasure a piercing voice acrobatics costume
a mixture of two or more things
sheng
dan
jing
chou
history
main roles
skills needed
Beijing Opera
Task 2:
Listen and use the Strategies to answer the questions.
1. Where was Beijing Opera performed at the beginning?
2. Why does it have very loud music and a piercing singing style?
3. Why do performers wear brightly coloured costumes?
1. Where was Beijing Opera performed at the beginning?
(2)Φ是有正负的标量
二． 磁体和通电导线之间的相互作用
练习3.条形磁铁放在水平面上，在它的上方偏右 处有一根固定的垂直纸面的直导线，如图所示，
当直导线中通以图示方向的电流时，磁铁仍保持 静止.下列结论正确的是 （ ） A.磁铁对水平面的压力减小 B.磁铁对水平面的压力增大 C.磁铁对水平面施加向左的静摩擦力 D.磁铁所受的合外力增加
思考： 若直导线放在条形磁铁上方偏左处， 则结论如何？
小结：
求电流对磁体的作用力，一般 是求磁体对电流的反作用力
三．速度选择器
练习5、如图5所示，在正交的匀强电场和磁场 的区域内（磁场水平向内），有一离子恰能沿 直线飞过此区域（不计离子重力） [ ]
A．若离子带正电，E方向应向下 B．若离子带负电，E方向应向上 C．若离子带正电，E方向应向上 D．不管离子带何种电，E方向都向下
磁场、安培力、 洛伦兹力
磁场、安培力、洛伦兹力练习题 答案
1.ABC 2. BC 3.D 4.D 5.C 6.BD 7.D 8.A 9.A. 10.AC 11. 0.2T, 2×10-3Wb, 0 12. 1T
一.磁通量 及其变化量 的求解 1.磁通量的求解 2.磁通量的变化量的求解
小结：
(1)φ= BS （ B或S一定是垂 直的有效值）
四．综合知识的应用
变式训练3. 如图，金属杆ab的质量为m， 长为L，通过的电流为I，处在磁感应强度 为B的匀强磁场中，结果ab静止且紧压于 水平导轨上。若磁场方向与导轨平面成θ 角，求：
(1)棒ab受到的摩擦力； (2)棒对导轨的压力。
第16题
小结：
解题方法： （1）画出截面图 （2）对物体进行受力分析 （3）根据平衡条件或牛顿第二定律列