Question

How would you produce a uniform electric field of 500 N/C?  Only one of the following methods will do it.  Choose one method and answer the corresponding question.   

A.   Charged conducting sphere of radius = 0.2 meter.  What charge must be on the sphere?

B.   Very long charged conducting cylinder of radius 0.2 m.  What linear charge density is required?

C.   Two large area conducting plates separated by 0.1 m.  What must be the charge density on the plates?

Answer 1

A) Let Q is the charge on the sphere.

use, E = k*Q/R^2

==> Q = E*R^2/k

= 500*0.2^2/(9*10^9)

= 2.22*10^-9 C <<<<<<<<<<------------------Answer

B) let lamda is the linear charge density required.

use, E = 2*k*lamda/R

==> lamda = E*R/(2*k)

= 500*0.2/(2*9*10^9)

= 5.56*10^-9 C/m <<<<<<<<<<------------------Answer

C) let sigma is the surface charge density on the plates.

use, E = sigma/epsilon

==> sigma = E*epsilon

= 500*8.854*10^-12

= 4.43*10^-9 C/m^2 <<<<<<<<<<------------------Answer