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:
Answer & explanation
Correct answer: option 1
The speed of the electromagnetic wave in vacuum is $\mathrm{c}=\frac{1}{\sqrt{\mu_0 \varepsilon_0}}=3 \times 10^8 \mathrm{~ms}^{-1}$
Air acts almost as vacuum, therefore
$3 × 10^8=a × 10^8$
or a = 3 (approximately)