# Electric potential of insulating rod

1. Feb 29, 2004

### pattiecake

This hmwk. problem has got me totally buggin...

A uniformly charged insulating rod of length 20cm is bent into the shape of a semicircle (so it looks like the letter "C"). The rod has a total charge of -8.50e-6C. Find the electric potential at a point P, in the center of the semicircle.

I know crazy things happen to electric potential when dealing with insulators...also, will this problem involve integrals?

If anyone has a clue I'd appreciate the guidance! Thanks in advance!

2. Mar 2, 2004

### pattiecake

Why will noone respond? =(

3. Mar 3, 2004

### paul11273

Yes, this requires and integral.

$$V=ke \int{dq/r}$$
$$V =ke(Q/r)$$

Where Q is the total charge of the rod and r is the radius this rod makes. Remember that circumference=2*pi*r, so use that to find r.