# Homework Help: EM - Capacitor -

1. Feb 14, 2006

### dekoi

A circular parallel plate capacitor has plates of radius 0.1m; the plates are separated by 0.10 mm. A current is supplied to charge the capacitor. While charging, the potential difference across the capacitor increases by 10 V/μs.

What is the magnitude of the rate of change of the electric field between the capacitor plates? Answer= 1 x 10^11 V/m.

What exactly is the "rate of change of the electric field"? dE/dt? dΦ/dt? Φ?
I have tried different methods using all three of those and have yet to receive the correct answer.

I am using: ⌡E.dA = Q/ε for dE/dt
and Φ= Q/ε for dΦ/dt and Φ

2. Feb 14, 2006

### Staff: Mentor

I get the correct answer. What is the equation for electric field, in terms of voltage and distance? You are given dV/dt, and the separation distance....

Just watch your units and exponents.

3. Feb 14, 2006

### dekoi

Wow! Thanks for the quick reply, I'm in urgent need right now.

Thank you for the information, as it helped me get the right answer.