An unknown charge sits on a conducting solid sphere of radius 13 cm. If the electric field 21 cm from the center of the sphere has magnitude 3.7 × 103 N/C and is directed radially inward, what is the net charge on the sphere?

Charge on the sphere will be equal to    

Explanation:

We have given radius of the sphere a = 13 cm

And electric filed 21 cm from the center is

So distance from the center r = 21 cm

We have to find the charge on the sphere

As

So according to Gauss law electric field is equal to

So

So charge on the sphere will be equal to