Refraction of waves
Different materials have different densities - this can cause waves, such as light, to change direction at the boundary between materials. This change in direction is called Process by which a wave changes speed and sometimes direction upon entering a denser or less dense medium, eg a light ray changes direction when refracted by a lens..
Light waves across boundaries
It is important to be able to draw Diagram that represents the direction and angle of travel of light. to show the refraction of a wave at a boundary.
Glass is denser than air, so a light ray passing from air into glass slows down. If the ray meets the boundary at an angle to the An imaginary but useful line at right angles to the boundary between air/glass. All angles are measured to this line., it bends towards the normal.
The reverse is also true. A light ray speeds up as it passes from glass into air, and bends away from the normal by the same angle.
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Refraction can cause optical illusions as the light waves appear to come from a different position to their actual source.
