How does eddy current circulation occur in a moving conductor?

[Delzac]

Homework Statement

I understand that when a conductor ( we assume that it is a thin square sheet with no resistance) move say with a constant velocity perpendicular to a uniform B-field, there will be a current induced in the conductor (eddy current). This induced current will oppose the change in the magnetic flux going through the sheet, i.e. oppose he motion of the sheet.

My question here is how does the current circulate in the sheet? I find it very hard to imagine a configuration that does this.

------------------------
l ---------------------- l
l ----------------------l---------------> Velocity
l------------------------l
l -------------Sheet--- l B- field points out of your screen.
------------------------

Any help will be greatly appreciated.

 

[Quinzio]

You may find useful this Wikipedia image.

 

[Delzac]

If the plate is moving in free space with no gravity, does this mean that there will be a torque?

 

[Delzac]

Any help would be great.

 

[Quinzio]

If the plate is moving in free space with no gravity, does this mean that there will be a torque?

Why do you expect a torque ?

 

[Delzac]

It looks like the plate has a north and south pole, so under the influence of the field (as given in the picture) the top of the plate will be attracted downwards and the bottom part of the plate upwards.

 

[Quinzio]

It looks like the plate has a north and south pole, so under the influence of the field (as given in the picture) the top of the plate will be attracted downwards and the bottom part of the plate upwards.

Yeah, that's ok, but it will not generate a torque (a spin), but rather a force in the opposite direction of the movement. That is why eddy currents can be used as "electric brakes" in some applications.

 

[Delzac]

I understand that there will be a force generated to brake the plate.

But, from the picture, based on the circular pattern in the current flow, wouldn' there be a magnetic field generated. So, base on the right hand corkscrew rule, the pole on the top is north and the bottom part is south, thus the plate will flip.