Question

The frequency in rad/sec of a wave with velocity of that of light and phase constant of 20 units is (in GHz)

(a) 6

(b) 60

(c) 600

(d) 0.6

I got this question in an interview for internship.

My question comes from Plane Waves in Dielectrics topic in portion EM Wave Propagation of Electromagnetic Theory

Answer 1

Right choice is (a) 6

The explanation: The velocity of a wave is given by V = ω/β. To get ω, put v = 3 x 10^8 and β = 20. Thus ω = vβ = 3 x 10^8^ x 20 = 60 x 10^8 = 6 GHz.