Question

A cylindrical shell of radius 7.00 cm and length 2.30 m has its charge uniformly distributed on its curved surface. The magnitude of the electric field at a point 18.1 cm radially outward from its axis (measured from the midpoint of the shell) is 36.0 kN/C. (a) Find the net charge on the shell.

(b) Find the electric field at a point 4.00 cm from the axis, measured radially outward from the midpoint of the shell.

Answer 1

Given is:-

Radius of the cylindrical shell R=7cm or 0.07m

length l=2.30m

Now,

part-a

The electric field due to cylindrical shell as infinitely long straight conductor is,

where  

or

plugging all the values we get

which gives us

Part-b

The expression for the electric field from the axis to the midpoint of the shell is,

Since the field at the distance from the axis to the point is less than the radius of the shell

thus

.

Thus the electric field at this point will be zero

hence