The electric field just above the surface of the charged drum of a photocopying machine has a magnitude E of 2.5 × 105 N/C. What is the surface charge density on the drum, assuming that the drum is a conductor?

Explanation:

Given data

Electric Field E=2.5×10⁵ N/C

To find

Charge Density

Solution

From definition of charge density we know that:

Charge Density=Electric field×Permttivity

Where Permttivity ∈₀=8.85×10⁻¹²C²/N.m²

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach