Waves Definitions Flashcards
Amplitude
A wave’s maximum displacement from its equilibrium position.
Antinodes
A position of maximum displacement in a stationary wave
Coherence
Waves with the same frequency and constant phase difference. There are two types of coherence: spatial and temporal coherency. They must also be coming from the same source to avoid a change in phase difference.
Constructive Interference
The type of interference that occurs when two waves meet in phase. The wave amplitudes are superposed.
Critical Angle
The angle of incidence that results in an angle of refraction of exactly 90o . It is when the refracted ray travels along the boundary line.
Destructive Interference
The type of interference that occurs when the two waves are in antiphase. When one wave is at a peak and one is at a trough their addition results in a minimum point
Diffraction
The spreading of waves as they pass through a gap of a similar magnitude to their wavelength.
Displacement
The distance that a point on a wave is from its equilibrium position
Electromagnetic Spectrum
The spectrum of electromagnetic waves, consisting
of Gamma Rays, X-Rays, Ultraviolet, Visible Light, Infrared, Microwaves and Radiowaves.
Electromagnetic Waves
Waves that consist of perpendicular electric and magnetic oscillations. All electromagnetic waves travel at the speed of light in a vacuum.
Frequency
The number of waves that pass a point in a unit time period. It is the inverse of the time period.
Fundamental Mode of Vibration:
The oscillation of a wave at its natural frequency
Intensity
The power transferred per unit area. It is proportional to the square of a wave’s amplitude.
Interference
The superposition of the amplitudes of waves when they meet
Longitudinal Waves
A wave with oscillations that are parallel to the direction of
energy propagation. Sound waves are an example of a longitudinal wave. They cannot travel through a vacuum.
Nodes
A position of minimum displacement in a stationary wave
Path Difference
A measure of how far ahead a wave is compared to another wave, usually expressed in terms of the wavelength.
Period
The time taken for a wave to complete one full cycle
Phase Difference
The difference in phase between two points on a wave. It is usually expressed in radians.
Polarisation
The restriction of a wave so that it can only oscillate in a single plane. This can only occur for transverse waves
Progressive Waves
Waves that transfer energy from one point to another
without a transfer of matter.
Reflection
The bouncing of a wave at a boundary. The angle of incidence will equal to the angle of reflection
Refraction
The changing of speed of a wave as it passes into a new medium. If light passes into an optically denser medium, it will slow down.
Refractive Index
A material property that is equal to the ratio between the speed of light in a vacuum, and the speed of light in a given material.
Stationary Wave
A wave that stores, but does not transfer, energy
Superposition
When two waves meet at the same point in space their
displacements combine and the total displacement at that point becomes the sum of the individual displacements at that point.
Total Internal Reflection
An effect that occurs in optical fibres, where full
reflection occurs at the inside boundary of the fibre, meaning no radiation passes out. The angle of incidence must be greater than the critical angle for this to occur. The incident ray must also be travelling in a more dense medium into a less dense medium.
Transverse Waves
A wave with oscillations that are perpendicular to the
direction of energy propagation. Electromagnetic waves are examples of transverse waves.
Wavelength
The distance between two identical positions on two adjacent waves. It is commonly measured from peak to peak or trough to trough
Young Double-Slit Experiment
An experiment that demonstrates the diffraction of light by passing monochromatic light across two narrow slits and observing the resulting pattern of bright and dark fringes.
