Hello Sunil,

Your question is quite simple, the answer to your problem can be obtained by using the formula,

E*2*pi*d*epsilon=lambda

where epsilon is the permitivitty of free space, and lambda is the linear charge density.

Substitute the values, as given in the question,

E=9*10^4 N/C

pi=3.14

epsilon=9 × 10 ⁹ N m ² C ⁻²

and d=0.02m

Hope this Helps