Q141 / 180 · AIIMS 2002 · Physics

Velocity of light is equal to

  • A
    $\sqrt{\varepsilon_0 \mu_0}$
  • B
    $\sqrt{\varepsilon_0 / \mu_0}$
  • C
    $\varepsilon_0 / \mu_0$
  • Correct answer
    D
    $\sqrt{\frac{1}{\varepsilon_0 \mu_0}}$.

Solution

Relation for velocity of light $(c)=\sqrt{\frac{1}{\varepsilon_0 \mu_0}}$ (where $\varepsilon_0=$ permittivity constant equal to $8.85 \times 10^{-12} \mathrm{~F} / \mathrm{m}$ and $\mu_0=$ permeability constant equal to $1.26 \times 10^{-6} \mathrm{H} / \mathrm{m}$. Numerically velocity of light $(c)=\sqrt{\frac{1}{\varepsilon_0 \mu_0}}$ $$ =\sqrt{\frac{1}{\left(8.85 \times 10^{-12}\right) \times\left(1.26 \times 10^{-6}\right)}} \approx 3 \times 10^8 \mathrm{~m} / \mathrm{s} \text {. } $$

Hence, the correct answer is option: 'D'.

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