1. Mar 20, 2007

### weskerq8

1. The problem statement, all variables and given/known data
Part A:
At a distance of 0.192 cm from the center of a charged conducting sphere with radius 0.100 cm, the electric field is 445 N/C. What is the electric field 0.614 cm from the center of the sphere?

Part B :
At a distance of 0.212 cm from the axis of a very long charged conducting cylinder with radius 0.100 cm, the electric field is 445 N/C. What is the electric field 0.590 cm from the axis of the cylinder?

Part C :
At a distance of 0.192 cm from a large uniform sheet of charge, the electric field is 445 N/C. What is the electric field 1.35 cm from the sheet?

2. Relevant equations

sorry guys but i don't know anything at physics i am bad at it

3. The attempt at a solution

2. Mar 21, 2007

### cristo

Staff Emeritus

3. Mar 21, 2007

I'm going to be a little bit nicer than Cristo, and say use Gauss' Law. The first one you can use$E = \frac{1}{4 \pi \epsilon} \frac{Q}{r^2}$, it should give the same answer as the answer obtained from Gauss' law. The other two I think will need Gauss' law.

4. Mar 21, 2007

### cristo

Staff Emeritus
There are two reasons for asking that the student shows his work; firstly, to gauge whether he has put any effort into thinking about the question, and secondly to identify his level of expertise which will assist us in composing an answer. For example, does th OP know how to derive the expression you give (which is Gauss' law on the sphere) from the general form of Gauss' Law?

5. Mar 21, 2007

I am not telling him/her the answer, I am simply saying how it could be done, and so I haven't done the question for them at all, they still need to do it, and secondly, if the OP doesn't know what gauss' law is then they can ask, and hence learn, either way I am pointing them in the right direction, but certainly not doing the problem for them.

P.S. By the way the OP said that they had no idea I'm assuming that they do not have any original mathematics, and so don't know where to start, it is for that reason that I said use gauss' law.

6. Mar 21, 2007

### KingNothing

Gauss's law has nothing to do with this problem, unfortunately.

To the OP: What is the relationship between distance and magnitude of the electric field?

Hint: It is the same as the relationship between sound intensity and distance from the source. Look up "inverse square rule".