# Estimating electric field strength

1. Mar 14, 2010

### Linus Pauling

1. Estimate the electric field (strength and direction) at the point A.

5cmx5cm gridL

2. E = -dV/ds

3. I had four options, each a combination of 500 or 1000V/m for the E field strength and then left or right for the direction. I knew it must be to the left because the field points in the direction of decreasing potential, but how was the strength obtained (the answer is 500V/m)?

I did E = dV/ds = 12.5V/.00625m = 2000V/m, because point A is 1/8(5cm) from the left side of the grid....