Physics Unit 3 Waves and Light (Definations)

Wave

A disturbance that transfers energy from one point to another without transferring matter.

Transverse Wave

A wave in which the particles of the medium oscillate perpendicular to the direction of wave propagation.

Longitudinal Wave

A wave in which the particles of the medium oscillate parallel to the direction of wave propagation.

Wavefront

A line or surface connecting adjacent particles that are in phase, such as all crests.

Amplitude

The maximum displacement of a particle in a wave from its undisturbed or rest position.

Wavelength

The distance between two consecutive points in phase on a wave, such as from crest to crest.

Frequency

The number of complete wave cycles produced or passing a point per second.

Period

The time taken for one complete wave cycle to pass a point.

Laws of Reflection

State that the incident ray, reflected ray, and normal all lie in the same plane, and the angle of incidence equals the angle of reflection.

Refraction

The change in direction of a wave as it crosses a boundary between two media of different optical densities, caused by a change in wave speed.

Laws of Refraction

State that the incident ray, refracted ray, and normal all lie in the same plane, and Snell's law applies.

Snell's Law

For light traveling between two given media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.

Refractive Index

The ratio of the speed of light in a vacuum to the speed of light in a medium.

Critical Angle

The angle of incidence in the optically denser medium for which the angle of refraction in the less dense medium is 90 degrees.

Total Internal Reflection

The complete reflection of a light ray back inside an optically denser medium when the angle of incidence exceeds the critical angle.

Diffraction

The spreading of waves as they pass through a narrow gap or around the edge of an obstacle.

Electromagnetic Spectrum

A continuous range of electromagnetic waves arranged in order of wavelength or frequency, all traveling at the speed of light in a vacuum.

Dispersion

The separation of white light into its component colors when passed through a prism, due to different speeds and refractive indices for each color.

Real Image

An image formed by the actual intersection of light rays, which can be projected onto a screen.

Virtual Image

An image formed by the apparent intersection of light rays, which cannot be projected onto a screen.