Question 1.2:
The electrostatic force on a small sphere of
charge 0.4 µC due to another small sphere of charge − 0.8 µC in air is 0.2 N.
(a) What is the distance between the two spheres? (b) What is the force on the
second sphere due to the first?
Answer:
(a) Electrostatic force on the first sphere, F =
0.2 N Charge on this sphere, q1 = 0.4 µC = 0.4 × 10−6 C
Charge on the second sphere, q2
= − 0.8 µC = − 0.8 × 10−6 C Electrostatic force between the spheres is
given by the relation,
Where, ∈0 = Permittivity of free space
(b) Both the spheres attract each other with the
same force. Therefore, the force on the second sphere due to the first is 0.2
N.
