Lesson_4.6_Homework_and_Solutions

# Lesson_4.6_Homework_and_Solutions - Lesson 5.1 Homework...

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Lesson 5.1 Homework Solutions 1. If light is incident from air into water at an angle of incidence of 30 o , what is the angle of refraction in water if the refractive index of water is 1.33? Solution Angle of incidence θ 1 = 30 o , refractive index of air n 1 = 1, n 2 = 1.33 1 2 2 1 sin sin n n θ = 1 2 1 2 1 sin sin sin 30 0.376 1.33 o n n = = × = θ 2 = sin -1 (0.376) = 22 o 2. If light is incident from water into air at an angle of incidence of 30 o , what is the angle of refraction in air if the refractive index of water is 1.33? Solution Angle of incidence θ 1 = 30 o , refractive index of water n 1 = 1.33, n 2 = 1 1 2 2 1 sin sin n n = 1 2 1 2 1.33 sin sin sin 30 0.665 1 o n n = = × = θ 2 = sin -1 (0.665) = 41.7 o 3. The spiral galaxy in the Andromeda constellation is 2 × 10 19 km away from the earth. What is this distance in light years? Solution A light year is the distance light will travel in one year. The speed of light in free space is c = 3 × 10 8 m.s -1 . One light year = 3 × 10 8 m.s -1 × 3600 s × 24 × 365 = 9.46 × 10 15 m = 9.46 × 10 12 km 1 6 9 12 2 10 km Number of light years 9.46 10 km 2.1 10 × = × × =

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4. If the refractive index of water is 1.33 and that of glass is 1.5, find the speed of light in water and in glass. Solution Speed of light in free space Refractive index Speed of light in the medium = 8 8 -1 -1 3 10 m.s Speed of light in water 1. 2.26 10 m
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Lesson_4.6_Homework_and_Solutions - Lesson 5.1 Homework...

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