Question

The electrostatic force between two point charges kept at a distance d apart, in a medium εr = 6, is 0.3 N. The force between them at the same separation in vacuum is
(a) 20 N
(b) 0.5 N
(c) 1.8 N
(d) 2 N

Answer 1

As we know from Coulombs law,
F = kq₁q₂/r² -----(1)
Here, k is kappa constant , k = 1/4πε₀
ε₀ is permittivity of vaccum.

For a medium , permittivity = εr
∴ force = 1/4πε₀εr × kq₁q₂/r²
From equation (1),
Force = F/εr
Given, force = 0.3 N
0.3 = F/6 ⇒ F = 0.3 × 6 = 1.8 N

Hence, option (c) is correct

Answer 2

Explanation:

Option (C) 1.8 N is correct option