magnetic induction 2

1. (a) Block C (b) Block A (c) Block A
The results are due to production of eddy current that consumes away part of the gravitational potential energy during falling.

2. When the magnet rotates, the filed lines associated with the magnet also rotate. As such, the copper disk is cutting these field lines and induced current is produced. By Lenz's Law, the disk must rotate in the same direction as the magnet to prevent the cutting of field lines.

3. Can't downoad the question.

4. The answer is option B.
The magnetic field lines run from right to left. The current flows in direction XWZY. Apply Fleming's Left Hand Rule.

5. Option D.
The vertical magnet produces field lines. The poles of the horizontal magnet move along or against the field lines.

6. Can't download question.


2014-10-21 15:32:06 補充：
3. The loop leaves the magnet at a speed lower than it should be if the magnet is not present.
A repulsice force acts on the loop when it is above the magnet, and an attractive force when it is below the magnet.

2014-10-21 15:41:17 補充：
6. Statements 1 and 2 are correct. The reason is straight forward.

2014-10-21 15:46:23 補充：
6.(cont'd)...
Statement 3 is correct. Before applying the magnetic field (but with current flows through S), the potentiometer is adjusted such that the millivoltmeter reads zero...

2014-10-21 15:46:53 補充：
(cont'd)...
6.(cont'd)...
This is to ensure that the two connection points on the slice are at the same potential, i.e. they are exactly opposite to one another.