Chapter 15 Refraction

When light goes from one medium into another, it changes speed When light goes from one medium into another, it changes speed. If light comes in at an angle, this causes it to change direction.

normal light qi Light is faster Air Water slower qr

normal light qi Light is slower Glass Air faster qr

wave crests l Air l smaller Water slower

speed of light in medium The Index of Refraction is a measure of how much light slows down in a medium compared to its speed in a vacuum speed of light in a vacuum 3 x 108 m/s index of refraction speed of light in medium

Indices of Refraction material n diamond 2.419 flint glass 1.66 H2O ice 1.309 water 1.333 air 1.000293 vacuum 1

When light goes from a lower “n” to a higher, it bends toward the normal and vice-versa. air glass

Draw where the light would go as it changed media glass air

Refraction changes the apparent positions of objects in different media.

Snell’s Law nisinqi = nrsinqr 43° 30.8° What is the angle of refraction? air n = 1 water n = 1.33 30.8°

Ray 1: Parallel, then through f Ray 2: Through f, then parallel Ray Diagrams for Convex Lenses f f Ray 1: Parallel, then through f Ray 2: Through f, then parallel Ray 3: Through the lens center

Ray Diagram for Concave Lenses