Question

Light is an electromagnetic wave. Its speed in vacuum is given by the expression

• A. $\sqrt{\mu_{0}\varepsilon_{0}}$
• B. $\sqrt{\frac{\mu_{0}}{\varepsilon _{0}}}$
• C. $\sqrt{\frac{\varepsilon_{0}}{\mu_{0}}}$
• D. $\frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}$

Answer 1

Answer: (D)

$\frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}$

Answer 2

$\mu_{0}=4 \pi \times 10^{-7} Wb A ^{-1} m ^{-1}$
$\varepsilon_{0} =8.85 \times 10^{-12} \frac{ N - m ^{2}}{ C ^{2}}$
So, $c =\frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}=3 \times 10^{8}\, m / s$