# Homework Help: Error for Electric Field Calculation

1. Feb 12, 2010

### bphysics

1. The problem statement, all variables and given/known data
Need to calculate an electric field $$\left|E\right|$$. I'm calculating this off of a map of equi-potential lines and electric field lines which have been determined by semiconducting paper.

I then need to calculate the error -- this is where I am having trouble.

2. Relevant equations

$$\left|E\right| = \frac{\Delta V}{\Delta l}$$

$$\frac{\delta E}{E}\right)= \sqrt{\left(\frac{\delta V}{V}\right)^2 + \left(\frac{\delta l}{l}\right)^2}$$

3. The attempt at a solution

I'm not 100% sure I understand how to use this equation for error. Can anyone offer any assistance?