Answer to Question #117537 in Electric Circuits for pescales

Question

1. A spherical conducting shell is placed in a time-varying magnetic field. Is there an induced current along the equator?
2. A rectangular loop moves across a uniform magnetic field but the induced current is zero. How is this possible?

Answer 1

1.

Yes,The induced current will produce a magnetic field to oppose the change in magnetic field

2.

Because, there is no change to the flux passing through the loop. Suppose we're looking at a diagram of a 3cm tall rectangle on a page and the uniform field is into the page (it won't matter how wide the rectangle is for this explanation). Now, if you slide the rectangle, say, 1cm to the right, you win 3cm^2 of field on the right side but you lose 3cm^2 of field on the left side, and these cancel out (because the field is uniform).