Question

The ratio of the forces between two charges placed at a certain distance apart in the air and by the same distance apart in a medium of dielectric constant K is ______.

Options

• 1 : K²

• K : 1

• K² : 1

• 1 : K

Answer 1

The ratio of the forces between two charges placed at a certain distance apart in the air and by the same distance apart in a medium of dielectric constant K is K : 1.

Explanation:

The force between two charges in the air,

`F_1 = 1/(4piε_0) . (q_1q_2)/r^2` ..............(i)

Similarly, the force between them in the medium of dielectric constant K.

`F_2 = 1/(4piε_0K) (q_1q_2)/r` ..............(ii)

From Eqs. (i) and (ii), we get,

F₁/F₂ = K ⇒ F₁ : F₂ = K : 1