# Basic electric field questions

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1. May 6, 2017

### DivideBy0

1. The problem statement, all variables and given/known data
I'm confused about [question 16](http://image.prntscr.com/image/41a5c611927c44a7ac30104be3dd10ee.png) and [question 30](http://image.prntscr.com/image/a6aea3b9a8f04df9aca0dfe14054d4ce.png). The correct answers are e and a respectively.

2. Relevant equations

3. The attempt at a solution

For 16, why did D not work? Intuitively, I chose E because of parallel plates that have equal electric fields, but what is the integral for choice D and E and why are they different?

For 30, I thought higher voltage meant higher potential so I thought the answer should be C and D. Why is it A?

2. May 7, 2017

### kuruman

Welcome to PF, DivideBy0.

16. The graph shows a uniform charge distribution, independent of x. Consider the charge distribution described in D. What does it look like? What do you know about the electric field that results from such a distribution?

30. You need to consider only one thing. The magnitude of the electric field can be approximated by $|\vec{E}|=|\frac{\Delta V}{\Delta s}|$. Where is this ratio the greatest?