Question

Positive charge is sprayed onto a large non-conducting belt above the left hand roller. The belt carries charge with a uniform surface charge density $\sigma$, as it moves with a speed $v$ between the rollers as shown. The charge is removed by a wiper at right hand roller. Correct option regarding the fields near the belt on the either side.

Answer 1

the strength of the electric field of an infinite plane charge is independent of the distance from the plane, and it is directly proportional to sigma. Let the constant of proportionality be 'k'

k*sigma*cos(theta)=mgsin(theta)

therefore, sigma is proportional to tan(theta)