Charge of uniform density (80 nC/m3) is distributed throughout a hollow cylindrical region formed by two coaxial cylindrical surfaces of radii, 1.0 mm and 3.0 mm. Determine

the magnitude of the electric field at a point which is 4.0 mm from the symmetry axis.

The electric field is given by 4.5 N/C.

Explanation:

Charge density = 80 nC/m3

inner radius, r' = 1 mm

outer radius, r'' = 3 mm

distance,  r = 4 mm

The linear charge density is given by

The electric field is given by

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

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray