Question

30. A monochromatic ray of light strikes the surface of transparent medium at angle of incidence 60° and get refracted into the medium an angle of refraction 45°
What is the refrethe Index of the medium?


I need with explaintion
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Answer 1

Given :

Angle of incidence = 60°

Angle of refraction = 45°

To Find :

Refractive index of the medium.

Solution :

★ Laws of Refraction :

1] The incident ray, the normal to any refracting surface at the point of incidence and the refracted ray all lie in the same plane called the plane of incidence or plane of refraction.

2] sin(i) / sin(r) = constant for any pair of media and for light of a given wavelength. This is known as Snell's law$.$

• n₁ sin(i) = n₂ sin(r)

Refractive index of air = 1

By substituting the values;

➠ n₁ sin(i) = n₂ sin(r)

➠ 1 × sin 60° = n₂ × sin 45°

➠ √3/2 = n₂ × 1/√2

➠ n₂ = √3 × √2/2

➠ n₂ = √1.5 ≈ 1.21

★ Additional Information :

• Refractive index of a medium is defined as the factor by which speed of light reduces as compared to the speed of light in vacuum.
• More refractive index implies less speed of light in that medium, which therefore is called denser medium.