BITSAT 2019 Slot 2 Solved Paper

The electric field intensity at a point lying outside the sphere (non-conducting) is
E=

1

4πε0

.

q

r2

i.e.
E∝

1

r2

........(i)
The electric field intensity at the surface (r=R),
E=

1

4πε0

q

R2

⇒E∝

1

R2

where, R being the radius of sphere,
The electric field intensity inside the sphere is
E=

qr

4πε0R3

⇒E∝r
At the centre of sphere, r=0,∴E=0