Electromagnetic Waves - Result Question 17

17. If $\varepsilon_0$ and $\mu_0$ are the electric permittivity and magnetic permeability in vacuum, $\varepsilon$ and $\mu$ are corresponding quantities in medium, then refractive index of the medium is

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(a) $\sqrt{\frac{\varepsilon}{\varepsilon_0}}$

(b) $\sqrt{\frac{\varepsilon_0 \mu}{\varepsilon \mu_0}}$

(c) $\sqrt{\frac{\varepsilon_0 \mu_0}{\varepsilon \mu}}$

(d) $\sqrt{\frac{\varepsilon \mu}{\varepsilon_0 \mu_0}}$

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Answer:

Correct Answer: 17. (d)

Solution:

  1. (d) We know that velocity of electromagnetic wave in vacuum

$(v_0)=\frac{1}{\sqrt{\mu_0 \varepsilon_0}}$ and velocity of

electromagnetic wave in medium is

$(v)=\frac{1}{\sqrt{\mu \varepsilon}}$.

Therefore refractive index of the medium

$(\mu)=\frac{\text{ Vel. of E.M. wave in vacuum }(v_0)}{\text{ Vel. of E.M. wave in medium }(v)}$