There are 2 main laws of Refraction of Light

 

Law 1

The Incident Ray,Refracted Ray and Normal Ray all lie on the same plane

 

Law 2

The Ratio of sin of Angle of Incidence and Angle of Refraction is constant for a particular medium

This constant is called Refractive Index

It is actually called Refractive Index of the second medium with respect to the first medium.

Snell s Law - Teachoo.jpg

 

The second law of refraction is also called Snell's Law

 

Let's do some examples

Suppose for a ray of Light. Angle of Incidence = 37° and Angle of Refraction = 24°. Find Refractive Index
(Given: sin 37° = 0.6 and sin 24° = 0.4)

Example.jpg

A beam of light passes from air into a substance X. If the angle of incidence be 72° and the angle of refraction be 40°, calculate the refraction index of substance X.
(Given: sin 72° = 0.951 and sin 40° = 0.642 )

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  1. Class 10
  2. Chapter 10 Class 10 - Light - Reflection and Refraction

Transcript

Example Suppose for a ray of Light. Angle of Incidence = 37Β° and Angle of Refraction = 24Β°. Find Refractive Index (Given: sin 37Β° = 0.6 and sin 24Β° = 0.4) We know that Refractive Index = (𝑠𝑖𝑛 (𝐴𝑛𝑔𝑙𝑒 π‘œπ‘“ 𝑖𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒))/(𝑠𝑖𝑛 (𝐴𝑛𝑔𝑙𝑒 π‘œπ‘“ π‘Ÿπ‘’π‘“π‘Ÿπ‘Žπ‘π‘‘π‘–π‘œπ‘›)) Refractive Index = (𝑠𝑖𝑛 (37Β°))/(𝑠𝑖𝑛 (24Β°)) Refractive Index = 0.6/0.4 Refractive Index = 6/4 Refractive Index = 3/2 Refractive Index = 1.5 Example A beam of light passes from air into a substance X. If the angle of incidence be 72Β° and the angle of refraction be 40Β°, calculate the refraction index of substance X. (Given: sin 72Β° = 0.951 and sin 40Β° = 0.642 ) Given, Angle of incidence = ∠i = 72Β° Angle of Refraction = ∠r = 40Β° We have to find Refraction index of substance X By second law of refraction, Refractive index = sin⁑𝑖/sinβ‘π‘Ÿ = sin⁑〖72Β°γ€—/sin⁑〖40Β°γ€— = 0.951/0.642 = 951/642 = 317/214 = 1.48 Refractive index of substance X is 1.48

About the Author

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.