- #1

ehrenfest

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## Homework Statement

__A charged parallel-plate capacitor (with uniform electric field [itex]\mathbf{E} = E\hat{\mathbf{z}} [/itex]) is placed in__

an uniform magnetic field [itex]\mathbf{B} = B\hat{\mathbf{x}}[/itex]

an uniform magnetic field [itex]\mathbf{B} = B\hat{\mathbf{x}}[/itex]

(a) Find the electromagnetic momentum in the space between the plates.

(b) Now a resistive wire is connected between the plates, along the z axis,

so that the capacitor slowly discharges. The current through

the wire will experience a magnetic force; what is the total

impulse delivered to the system, during the discharge ?

__(c) Instead of turning off the electric field, suppose we slowly reduce__

the magnetic field. This will induce a Faraday electric field, which

in turn exerts a force on the plates. Find the total impulse.

the magnetic field. This will induce a Faraday electric field, which

in turn exerts a force on the plates. Find the total impulse.

I can do parts a) and b) so I do not think you need to read them. I need help with c).

## Homework Equations

## The Attempt at a Solution

I am stuck trying to find to find the electric field due to the changing B-field. What trick am I supposed to use? How can I figure out what direction it is in?