Refractionoflight onplanesurfacescurved

prepwalk

1. PHYSICS REFRACTION OF LIGHT ON PLANE SURFACES, CURVED SURFACES AND GLASS PRISMS Short revision series

2. Refractive index Refractive index = real depth apparent depth i r Medium 1 Medium 2

3. Laws of refraction The incident ray, the reflected ray and the normal at point of incidence all lie in the same plane SNELL’s law: The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media the constant is known as the refractive index a n g = sin i (air) = velocity of light in air sin r (glass) velocity of light in glass

4. Eg If the angle of refraction is 20 , What is the angle of incidence if the refractive index of air to glass is 1.5?

5. solution a n g = sin i/sin r 1.5 = sin i/sin 20 sin i = 1.5sin20 = 1.36 i = sin -1 1.36

6. Refraction of light through a trangular prism n = sin ½ (dm + A) sin ½ A A= refracting angle of prism dm = minimum angle of deviation i r r dm A

7. Total internal reflection and critical angle Total internal reflection occcurs when the critical angle is exceeded for light travelling from a dense to a less dense medium Critical angle is the incident angle at which the angle of refraction is 90 when light passses from a denser to a less dense medium. a n g = 1/sinC