Question

The velocity of e.m. waves in a medium is 2.5 × 10⁸ ms^–1. what is the dielectric constant of the medium? 

(A) 1.2 

(B) 1.44 

(C) 0.69 

(D) 1.6

Answer 1

The correct option is (B) 1.44.

Explanation:

velocity in a medium = [(velocity of light in free space) / √(εr)] 

∴ √(ε_r) = [(3 × 10⁸) / (2.5 × 10⁸)] = 1.2 

∴ ε_r = (1.2)² = 1.44