C.3 Wave Phenomena

Reflection

A wave encounters a boundary between two different media and bounces back. The angle of reflection is equal to the angle of incidence.

Law of reflection

the angle of incidence is equal to the angle of reflection

Refraction

The change in direction of a wave when it moves from one material to another at an angle, due to the difference in velocity of the waves in the two materials.

Transmission

When a wave passes across a boundary between two different media and continues to travel through the new medium.

Diffraction

The spreading of waves as they travel around a body or through an aperture.

Refractive index

A measure of how much a medium can slow down light waves. The ratio of the speed of light in a vacuum to the speed of light in the medium.

Snell’s Law

An equation that describes the angle of incidence and angle of refraction as light (or other waves) is refracted through a boundary between two media that have different refractive index.

Critical Angle

The angle of incidence at which light is refracted along the boundary between a medium with a greater refractive index and a medium with a smaller refractive index.

Total Internal Reflection

When the angle of incidence is greater than the critical angle at the boundary between a medium with a greater refractive index and a medium with a smaller refractive index. Light is completely reflected back into the medium with the greater refractive index.

conditions for total internal reflection:

The light must be passing from a medium with a higher refractive index into a medium with a lower refractive index.

The angle of incidence must be greater than the critical angle.

Crest

The highest point of a wave

Trough

The lowest point of a wave

Superposition

Two waves meet and their displacements add together at every point in space to produce a combined wave with a resultant displacement.

Constructive Interference

Occurs when two waves meet in phase (crests meet crests and troughs meet troughs), resulting in a wave with increased amplitude.

Destructive Interference

Occurs when two waves meet out of phase (crests meet troughs), resulting in a wave with decreased or zero amplitude.

Path Difference

The difference in distance that two waves travel from a source to a given point.

Coherent Waves

same wavelength (frequency)
a constant phase difference