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WorksheetsElectromagnetic induction 电磁感应
Total questions: 10
Worksheet time: 43mins
_________ law says that an induced current always moves in a direction so that its magnetic field opposes the change in original flux.
_________ 定律说明感应电流的方向，总是使其产生的磁场与原磁通量的变化相反。
Lenz's 楞次
Faraday's 法拉第
Ampere's 安培
如图所示，一铜环经过某长方形匀强磁场。针对位置1 至4，下列哪项叙述是错误的？
As shown in the figure, a copper ring passes through a rectangular uniform magnetic field. For positions 1 to 4, which of the following statements is wrong?
位置1，没有磁通量变化，没有感应电流
Position 1, no change in magnetic flux, no induced current
位置2，磁通量增加，产生感应电流
Position 2, magnetic flux increases, induced current produced
位置3，恒定磁通量，产生恒定的感应电流
Position 3, magnetic flux remains, steady induced current produced
位置4，磁通量减少，产生感应电流
Position 4, magnetic flux decreases, induced current produced
在 0.10 s 内，通过环形线圈的磁通量从4 x 10-5 Wb 增至 5 x 10-5 Wb，环形线圈的感应电动势是
Within 0.10 s, the magnetic flux through the ring coil increased from 4 x 10-5 Wb to 5 x 10-5 Wb, the induced electromotive force of the coil is
1 x 10-4 V
2 x 10-4 V
4 x 10-4 V
5 x 10-4 V
There is a closed springy coil in 2.0 T uniform magnetic field. First stretches the coil to an area of 15 cm2, then let it go and the coil shrink to an area of 5 cm2 in a time of 0.5 s. What is the induced emf of the coil?
在 2.0 T 均匀磁场中有一个闭合的弹性线圈。 首先将线圈拉伸到 15 cm2 的面积，然后放开，在0.5 s 线圈将收缩到 5 cm2 的面积。 线圈的感应电动势是多少？
0.25 mV
1 mV
4 mV
10 mV
How to increase the induced current?
如何增加感应电流？
Change carbon brush 换碳刷
Change position of the magnetic pole 改变磁极的位置
Use small scale Galvanometer 使用量程较小的表头
Increase number of coils 增加线圈数量
Find the length of a conductor which is moving with a velocity 0.4 m/s in a magnetic field of 8 T, inducing an emf of 20 V if magnetic field, velocity and length of conductor are mutually perpendicular to each other.
某导体在 8 T 的磁场中以 0.4 m/s 的速度运动，如果磁场、速度和导体的长度相互垂直，感应电动势为 20 V。求导体的长度。
50 m
5 m
6.25 m
0.5 m
一线圈产生的自感电动势为 5 V，自感系数为 1 mH，求线圈中的电流变化率。
The self-induced emf generated by a coil is 5 V and the self-inductance is 1 mH. Find the rate of change of the current in the coil.
5000 A s-1
500 A s-1
50 A s-1
0.005 A s-1
As shown in the figure, a coil is placed in a magnetic field. Which of the following conditions will result in a clockwise induced current?
如图所示，将线圈放置在磁场中。 以下哪个情况会产生顺时方向的感应电流？
Gradually increase the magnetic induction
逐渐增加磁感应强度
Keep the magnetic induction constant
保持磁感应强度
Gradually decrease the magnetic induction
逐渐减少磁感应强度
Gradually increase the coil area
逐渐增加线圈面积
What is necessary to induce eddy currents?
以下哪一项必须存在才能产生涡流？
A changing magnetic field
变化的磁场
A constant electric field
恒定电场
A constant magnetic field
恒定磁场
What will happen if the back emf of a DC motor vanishes suddenly?
如果直流电动机的反电动势突然消失，会发生什么事？
The motor will stop immediately
电动机将马上停止
The motor will run noisy
电动机将产生噪音
The armature may burn
电枢可能会被烧毁
