# A Lenz Law Question

1. Jan 11, 2009

### starless.aeon

A circuit contains a resistor and an uncharged capacitor. Pointing into the plane of the circuit is a uniform magnetic field (B). If the magnetic field increases in magnitude with time, which plate of the capacitor (top or bottom) becomes positively charged?

I don't understand how the hand rules play into this question, because of the capacitor. And I don't understand how I'm supposed to figure out which plate is positive and which is negative. Please help me out?

2. Jan 11, 2009

### Delphi51

A capacitor acts like a direct connection when it is uncharged, so ignore it while you use the hand rule to determine the direction of the current. Charge doesn't actually pass through a capacitor, so if positive current flows into a capacitor, it will charge that side of the capacitor positively.

3. Jan 11, 2009

### starless.aeon

OH. It makes this question so much easier now, thanks. bundles.

I've come to determine my upper plate is negative cause the electrons flow into it.

again, thanks so much.