# Method of images

1. Nov 1, 2013

### bg646

Hello, I am stuck with this one. Your help/comments would be most appreciated.

A charge "+Q" lies at a distance "d" above an infinitely large conducting plane. Applying the method of images, i found the right result that the total charge of the infinite plane is "-Q" and that the stored electric energy is:
$$W_{E}=-\frac{Q^{2}}{8\pi\epsilon_{0}d}$$
Since the stored electrostatic energy also satisfies:
$$W_{E}=CV^{2}/2$$

it seems that the capacitance of the system would be negative which must be non sense. Therefore the charge above the plane is *not* a capacitor.

Is this correct or am i missing something?