Question

The speeds of microwaves, infrared waves, and ultraviolet waves are Vm, Vi, and Vu respectively. Identify the correct combination showing the different waves in vacuum.

(a) Vm > Vi > Vu

(b) Vm = Vi = Vu

(c) Vm < Vi < Vu

(d) Vm > Vi < Vu

This question was posed to me at a job interview.

This question is from Electromagnetic Spectrum in division Electromagnetic Waves of Physics – Class 12

Answer 1

Correct choice is (b) Vm = Vi = Vu

To explain: The correct combination is ➔  Vm = Vi = Vu. This is because, in vacuum, all the electromagnetic waves in question will travel at the same speed. The speed with which they travel in vacuum is the speed of light. (c = 3 × 10^8 m/s).