# Help hw question driving me crazy!

1. Sep 19, 2006

### soconfused

help... urgent hw question driving me crazy!

Hi. I don't understand this hw question... and I mean I know that I have to use the absolute error and relative error for it, but I don't understand how to find the electric field with the potential difference and distance... I've been looking at it for a while now, and it's due in an hour. This is driving me nuts! Can anyone please help?

You measure 2 potentials and estimate their errors, (1.1+-0.028)V and 0.4V with the same error. You determine the potential difference between these voltages. With the measured distance of (5.543+-0.245)cm between the points where the voltages were measured and the potential difference you calculate the electric field in the region between the 2 points. What is the absolute error of the electric field (hint: calculate the absolute error of the voltage difference, convert it and the absolute error of the distance given to relative errors, calculate the relative error of the electric field, and then convert that to an absolute error.

I'm trying to follow the hint step-by-step, but do I have to double the error of the potentials? I dont know... i'm lost.

2. Sep 19, 2006

### soconfused

one more thing

If it helps, a similar problem, just with different numbers, but with the correct answer, is below.

You measure 2 potentials and estimate their errors, (1.1+-0.022)V and 0.4V with the same error. You determine the potential difference between these voltages. With the measured distance of (4.895+-0.212)cm between the points where the voltages were measured and the potential difference you calculate the electric field in the region between the 2 points. What is the absolute error of the electric field ?

ans: .8874515