Question

Q.11. light, of wavelength of 500 nm in air, enters a glass plate of refractive index 1.5 find (i) speed (ii) frequency and (iii) wavelength of light in glass. Assume that the frequency of light remains the same in both media?

Answer 1

Given:

Wavelength of light in air $= \lambda_a = 500\: nm$

                                          $= 500 \times 10^{-9}\:m$

Refractive index (μ) = 1.5

We know that,

$\mu = \frac{\text{Speed of light in air}}{\text{Speed of light in glass}}$

$\therefore \text{ Speed of light in glass}= \frac{3 \times 10^8 m/s}{1.5} = \frac{2 \times 10^8m/s}{1}$

Thus, speed of light in glass = $2 \times 10^8m/s$

ii)

Frequency of light in air $= \frac{\text{velocity of light in air}}{\text{wavelength of light in air}}$

                                        $= \frac{3 \times 10^8m/s}{500 \times 10^{-9}m}$

                                       $= \frac{3\times10^8}{5\times10^{-7}}$

                                       $= \frac{30\times 10^7\times 10^7}{5} = \frac{6\times 10^7\times10^7}{1}$

                                      $= 6\times10^{14} \text{Hz}$

Now frequency of light in air = frequency of light in glass

∴ Frequency of light in glass = $6\times10^{14}\text{Hz}$

Answer 2

Answer:

333.33 nm is the correct answer

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