Question

How many electrons must be removed from the metal sphere of radius 5cm so that it acquires a
charge of 4 x 10-15C. What is the electric intensity at a point (1) on the surface of the sphere (2) at
a point 4cm from the centre of the sphere, (3) at a point 4cm from the surface of the sphere and
(4) surface charge density of the sphere.​

Answer 1

Explanation:

Charge of each electron e=1.6×10

−19

C

Number of electrons removed from the sphere n=4×10

10

Thus total charged removed from the sphere q=ne

∴ q=4×10

10

×1.6×10

−19

=6.4×10

−9

C

Distance of point from the center of sphere r=20cm=0.2m

Thus electric field at that point E=

r

2

kq

where k=

4πϵ

o

1

=9×10

9

⟹ E=

(0.2)

2

9×10

9

×6.4×10

−9

=1440NC

−1

hope this will help you