1. Five Ways to Change the Direction of Light
Reflection, Diffraction, Refraction, Scattering,
And
Gravity

2. “The Angle of Reflection must equal the Angle of Incidence”
Reflection is when a wave (or for that matter anything) changes direction because it bounces off a surface
Light reflects
How the direction changes is governed by:
The Law of Reflection
“The Angle of Reflection must equal the Angle of Incidence”

3. Diffraction
Diffraction occurs when a wave changes direction going around an edge or spreading out after passing through a hole
Light is a wave and so diffracts.
The larger the wavelength the more the direction changes
(copy diagrams)

4. Refraction
Refraction is when a wave changes direction because it changes speed
As it moves into or out of a substance
How much the direction changes is directly related to:
The Angle of Incidence
The Frequency of the Wave
How much it slows down, or speeds up

5. “Scattering”
When light encounters a small particle the electro-magnetic fields created by the motion of the particle’s electrons makes the light change direction.
This is called “scattering”
How Much depends on:
The Size of the particle
The size of the Light wave.
The larger the particle the larger the wave it will scatter best.

6. Gravity
Einstein’s theory of relativity stated that gravity is a bend the very fabric of space-time itself caused by a mass
Thus Gravity should change the direction of light.
This effect is not normally noticeable.
But given enough mass it is.

7. In fact it been seen and measured for stars appearing from behind the Sun.
Thus confirming Einstein’s Theory of Relativity.