2.[感应电动势的大小计算公式] 1) E＝BLV (垂直平动切割)
2) …=?(普适公式) ε∝(法拉第电磁感应定律) 3) E= nBSωsin(ωt+Φ)；Em＝nBSω (线圈转动切割) 4)E＝BL2ω/2 (直导体绕一端转动切割) 5)*自感E自＝nΔΦ/Δt＝＝L ( 自感 )
1.法拉第电磁感应定律：电路中感应电动势的大小跟穿过这一电路的磁通量变化率成正比，这就是法拉第电磁感应定律。
内容：电路中感应电动势的大小，跟穿过这一电路的磁通量的变化率成正比。
4、圆周运动有关的对称规律：特别注意在文字中隐含着的临界条件
a、从同一边界射入的粒子，又从同一边界射出时，速度与边界的夹角相等。
b、在圆形磁场区域内，沿径向射入的粒子，一定沿径向射出。
注意：均匀辐射状的匀强磁场，圆形磁场，及周期性变化的磁场。
电磁感应：.
3、求粒子的运动时间：偏向角(圆心角、回旋角)=2倍的弦切角，即=2
×T
2、 求半径(两个方面)：①物理规律
②由轨迹图得出几何关系方程 ( 解题时应突出这两条方程 )
几何关系：速度的偏向角=偏转圆弧所对应的圆心角(回旋角)=2倍的弦切角
相对的弦切角相等，相邻弦切角互补 由轨迹画及几何关系式列出：关于半径的几何关系式去求。
1、 找圆心：①(圆心的确定)因f洛一定指向圆心，f洛⊥v任意两个f洛方向的指向交点为圆心；
②任意一弦的中垂线一定过圆心； ③两速度方向夹角的角平分线一定过圆心。
4．信的开头和结尾已给出，不计人句子总数。
Dear Rose，
________________________________________________________________________________________________
Wish you every Success．
Your teacher
Lin Lin
答案:
Dear Rose,
I'm happy to hear from you and know that you set your new goal and have begun your study in another school.
It is natural that you feel lonely in your new class as you did in your old one, but I'm sure you'll get along well with the other classmates in your new class if you find chances to make friends with them, in which way you'll find them just as understanding as your old ones.
The reason why you feel too tired and can't concentrate yourself may be that you don't organize your time well enough and can't get enough sleep. Don't work too late or too hard and you are likely to get less tired. Try to be more confident and you'll succeed.
Wish you every success.
Your teacher,
3．使用必要的连接词。
2．将5个句子组织成连贯的一篇短文。
1．必须使用5个句子介绍全部所给的内容。
2) 
…=?(普适公式) ε∝
(法拉第电磁感应定律)
3) E= nBSωsin(ωt+Φ)；Em＝nBSω (线圈转动切割)
4)E＝BL2ω/2
(直导体绕一端转动切割)
5)*自感E自＝nΔΦ/Δt＝＝L
( 自感 )
圆周运动有关的对称规律：特别注意在文字中隐含着的临界条件
=2倍的弦切角
，即
×T
=偏转圆弧所对应的圆心角(回旋角)