Quick physics question

[NeoMadHatter]

need some help on physics,

what are the electric field and electrostatic potential due to an infinite line of charge?

thanks in advance.

 

[zephyrprime]

I think I remember this.

The electric field strength = Q*e*1/(4*pi*r)

where Q is the charge density per meter.
e is the permitivity of space
r is distance from the line charge to the point under consideration

The potential is Q*e*ln(r)/(4*pi)

 

[zephyrprime]

Also, you should understand the derivation of the formulae.

Consider the point P. The field strength at P is simply the aggregation of the field emmited by each and evey bit of the wire.

So figure out the amount of force each bit of wire exerts on P and then sum them together. Since the charge line is continuous, you can integrate rather than sum.

Since the charge line is symmetrical, the vector potential parallel to the line charge will be zero. So the field emanating from the line charge is entirely perpendicular to the line.

F = Q*e*1/(4*pi*(sqrt(x^2 + r^2))^2) * r/sqrt(x^2 + r^2) * dx


Now integrate F from x=-infinity to x=infinity