Q. The dielectric constant of air is 1.006. The speed of electromagnetic wave travelling in air is $a \times 10^{8}ms^{- 1}$, where $a$ is about
A) 3
B) 3.88
C) 2.5
D) 3.2
Explanation
(a) For an electromagnetic wave
Velocity $c = \frac{1}{\sqrt{\mu_{0}\varepsilon_{0}}} = 3 \times 10^{8}ms^{- 1}$
Air acts almost as vacuum
$\therefore a = 3$ approximately
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.