State the laws of refraction of light. If the speed of light in vacuum is 3 × 10⁸ ms⁻¹, find the speed of light in a medium of absolute refractive index 1.5.

The laws of refraction states that,

1. First law: The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant. This is known as Snell’s law. Mathematically,

$fraction numerator sin space straight i over denominator sin space straight r end fraction space equals n subscript 12$

n₁₂is the relative refractive index of medium 1 with respect to medium 2.

2. Second law: The incident ray, refracted ray and the normal to the interface of the two media at the point of incidence, all the three lie in the same plane.

When light ray is propagating from medium 1 to medium 2, then the refractive index of medium 1 with respect to medium 2 is expressed as,

$straight n subscript 12 space equals fraction numerator speed space of space light space in space medium space 2 over denominator speed space of space light space in space medium space 1 end fraction space equals straight v subscript 2 over straight v subscript 1$ ; is the speed of light in medium 1 and 2.

Numerical:

Given, refractive index of the medium = 1.5

So, $straight n subscript straight m space equals fraction numerator speed space of space light space in space vaccum space over denominator speed space of space light space in space medium space end fraction space equals fraction numerator 3 space straight x space 10 to the power of 8 over denominator straight v end fraction$

$straight v equals space fraction numerator 3 space straight x 10 squared over denominator 1.5 end fraction space equals 2 space straight x space 10 to the power of 8 space straight m divided by straight s comma$ is the required speed of light in medium.

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State the laws of refraction of light. If the speed of light in vacuum is 3 × 108 ms−1, find the speed of light in a medium of absolute refractive index 1.5.

Light - Reflection and Refraction

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State the laws of refraction of light. If the speed of light in vacuum is 3 × 10⁸ ms⁻¹, find the speed of light in a medium of absolute refractive index 1.5.