Does Faraday's Law Indicate Charge Separation in a Loop?

[cair0]

So I'm studying for my physics final, and I ran across a problem that is giving me a bit of trouble.

http://cyclotron.tamu.edu/dhy/sample_final_exam.pdf

the question is 3b.

I'm thinking that the wire loop will have no induced current in it since there isn't a change in flux when you consider a loop rather than a bar, but it doesn't seem right that a 13 point problem would have such a simple answer.

 

[OlderDan]

So I'm studying for my physics final, and I ran across a problem that is giving me a bit of trouble.

http://cyclotron.tamu.edu/dhy/sample_final_exam.pdf

the question is 3b.

I'm thinking that the wire loop will have no induced current in it since there isn't a change in flux when you consider a loop rather than a bar, but it doesn't seem right that a 13 point problem would have such a simple answer.

I think you've got it. If you look at it from the point of view of charges moving with velocity v through a magntetic field, charges in both vertical parts of the loop will be forced in the same direction. There will be shift of charge until the electric force offsets the magnetic force, but no net current flow. Charges in the top and bottom of the loop just get pushed to the side of the wire.

 

[quasar987]

Dan,

what happens in the case of Figure (a)? Is there a separation of charges, positive ones accumulating at the top of the stick, negative ones at the bottom?

 

[OlderDan]

Dan,

what happens in the case of Figure (a)? Is there a separation of charges, positive ones accumulating at the top of the stick, negative ones at the bottom?

Yes, and the same thing would happen for the loop. Charge separates and builds up an electric field. There will be equilibrium when the electric force and the magnetic force are equal and opposite.