Use gauss' law to find the e field of an infinite solid cylinder of charge of radius r and charge density lambda per unit length. as usual, draw everything on the diagrams and label them.

Explanation:

As we know that electric field due to long cylinder on a cylindrical Gaussian surface must be constant

so on the Gaussian surface we will have

now the electric field is passing normally through curved surface area of the cylinder

so we will have

here enclosed charge in the cylinder is given as

from above equation

energy stored in the capacitor= 9.72 x 10⁻⁴ j

explanation:

the energy stored in the capacitor is given by

e= 1/2 c v²

e= energy stored

c= capacitance= 1.5 µc= 1.5 x 10⁻⁶f

v= potential difference=36 v

so energy stored= e= 1/2 (1.5 x 10⁻⁶) (36)²

energy stored= 9.72 x 10⁻⁴j