A beam of light is incident from air to water at an angle of 30^{}. Find the angle of refraction if the refractive index of water is 4/3

Correct Answer is : 22∘^{}∘

Correct Answer is : 22∘^{}∘

Test Index

JAMB Physics 2018 Paper

Question : 52

Total: 87

^{\circ}

Solution:

Concept:

Snell's law relates the angle of incidence to the angle of refraction using the refractive indices of the two media.

Explanation:

For light travelling from air to water,

n_1 = 1

and

n_2 = \frac{4}{3}

Given angle of incidence,

i = 30^\circ

Snell's law is:

n_1 \sin i = n_2 \sin r

Substitute values:

1 \times \sin 30^\circ = \frac{4}{3} \sin r

Since

\sin 30^\circ = 0.5

0.5 = \frac{4}{3} \sin r

Therefore,

\sin r = \frac{0.5 \times 3}{4} = 0.375

Taking the inverse sine:

r = \sin^{-1}(0.375) \approx 22.02^\circ

Thus the angle of refraction is approximately

22^\circ

Answer:

22^\circ

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