Equipotential Surfaces for Different Charge Configurations

[pat666]

Homework Statement

Sketch the equipotential surfaces which result from the following charge configurations:
(a) a point charge
(b) a spherically symmetric charge distribution
(c) a very large, plane, uniformly-charged sheet
(d) a long, uniformly-charged cylinder
(e) an electric dipole.

sorry I have posted this already but i figured since i mainly just need a check id stick it in a different thread.
I am pretty sure that a and e are correct, unsure of b and d and I need some help with c... thanks

Homework Equations

The Attempt at a Solution

 

[Onamor]

It might help understanding to think about these in terms of http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/gaulaw.html" .

B is wrong. D is probably better drawn in 3D if you can. For C, think about the gravitational field right at the surface of the Earth - this is a good approximation.

 

[pat666]

sorry but could you give me a bit more of a hand - I've never heard of Gauss' law (excluding the million things in maths he did) D i don't think i can draw in 3d?, b i have no idea what else to do and c i will look at the gravitational field right at the surface of the Earth now

 

[Onamor]

What will B look like from a huge distance away? (Think about stars in the sky! :rofl:)

D is misleading in 2D. If the marking is really picky it might even be wrong - remember how to draw field lines into and out of a page? to draw in 3D just draw a coke can, then rub out the ends or something!

 

[pat666]

been a year since i did this in high school but i think that x means out of page and dots mean in??

 

[pat666]

is this what you meant for d? (really dodgy)

 

[Onamor]

Its long, so you can ignore the effects at the ends presumably.

Describe what it should look like. Again, you can picture it from far away.

 

[pat666]

I really can't picture it ay. so for d if I cut off the ends will it be right then?