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.
Answers
Answer:
There are 2 Laws of Refraction of Light:
• First law of refraction also called as ‘Snells’s Law’: This law tells us about the amount of bending of light rays. It says that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.
• Second law of refraction: This law states that the incident ray, the refracted ray, and the normal to the interface of two media at the point of incidence − all lie in the same plane. If the light ray goes from medium 1 to 2 then the refractive index of medium 1 with respect to medium 2 is, where, v1 and v2 are the speeds of light in medium 1 and 2 respectively.
Solution:
We know that, refractive index = speed of light in vacuum/speed of light in a medium. Let the speed of light in a medium be ‘n’
therefore, 1.5=3×10^8/n
1.5n=3×10^8,
n=3×10^×10/1.5×10
=30×10^8/15
n=2×10^8 m/s
Hence, speed of light in a medium is 2*10^8m/s
Answer:
Explanation:
1st part -
There are two laws of refraction of light.
(a) The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant. This in known as Snell's law. Mathematically, it can be expressed as - Sin i/sin r = n₁₂
Here, n₁₂ is the relative refractive index of medium 1 with respect of medium 2.
(b) The incident ray, the refractive ray and the normal to the interface of two media at the point of incidence lie on the same path.
2nd Part -
Speed of light in vacuum = 3 × 10⁸ m/s
Refractive index of the medium = Speed of light in vacuum/Speed of light in medium
⇒ 1.5 = 3 × 10⁸/v
⇒ v = 2 × 10⁸ m/s
Hence, the speed of light in the medium of refractive index 1.5 is 2 × 10⁸ m/s.