Electrons can travel faster than the speed of light in certain media. When this happens, the electrons give off radiation known as Cerenkov radiation.

Complementary colours are two colours that can added together to produce white. For example, blue added to yellow produces white.

Planck's constant is

The De Broglie wavelength equation is

Diffraction is the phenomenon observed when waves appear in a region where a shadow, or no wave pattern, would be expected.

According to Doppler, as a source of sound moves towards a stationary observer, the pitch of the sound is higher and as it moves away, the pitch is lower.

Huygens' principle regards every point on a wave front as a source of secondary wavelets that spread out in the forward direction.

Destructive interference happens when two waves meet and the trough of wave A meets the crest of wave B. They cancel each other out and no wave pattern is observed.

The Principle of Superposition states that the resultant amplitude of two waves meeting at a point is given by the vector sum of the individual amplitudes at that point.

Secondary wavelets are waves that originate within an existing wave.

Ultraviolet refers to the portion of the spectrum with frequencies greater than violet light.

We use this equation to calculate the angle between the central line of a diffraction pattern and the dark lines.

Shock waves occur when an object travels through a medium faster than the speed at which the sound waves it produces move through the medium.