Question

A bar magnet sits inside a coil of wire that is connected to a meter. ( north end facing into the meter)

The bar magnet is pulled out of the coil, What can we say about the current in the meter?

a. The current goes from right to left.

b. The current goes from left to right.

c. There is no current in the meter.

d. Not enough information

I have the answer , i just need help with the explanation please!!

Answer 1

I think you have missed posting the figure of the motion of the magnet.I will describe both the cases for the case as shown in image below.

(1) If the bar magnet is pulled out with the north pole facing the coil as shown above Then we see that magnetic field going inside the coil reduces as the bar magnet moves away. As per lenz's law the coil will oppose the change , so it will try to increase the magnetic field going inside the coil , so the current flows clockwise to create magnetic field going inside the coil.In this case current flows from right to left(clockwise)

It can be understtod by one more explaination. As the magnet is moved out with north pole facing the coil, As per lenz's law the coil will oppose the relative motion so it will try to attract the bar magnet towards it.Hence it will become a south pole and starts attracting the bar magnet. It will become a south pole means the magnetic field lines will be coming inside this pole so the field going inside will increase . To create a filed which is going inside the coil (or to become south pole) the current flow should be clockwise i.e. from right to left in our case.