Chapter 4 - Waves Flashcards
Define Amplitude
A wave’s maximum displacement from its equilibrium position
Define Antinodes
A position of maximum displacement in a stationary wave
Define Coherence
Waves with the same frequency and constant phase difference
Define Constructive Interference
The type of interference that occurs when two waves
meet in phase. The wave amplitudes are superposed
Define Critical Angle
The angle of incidence that results in an angle of refraction of
exactly 90 degrees. It is when the refracted ray travels along the boundary line
Define 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.
Define Diffraction
The spreading of waves as they pass through a gap of a similar
magnitude to their wavelength.
Define Displacement
The distance that a point on a wave is from its equilibrium
position.
Define Electromagnetic Spectrum
The spectrum of electromagnetic waves, consisting
of Gamma Rays, X-Rays, Ultraviolet, Visible Light, Infrared, Microwaves and
Radiowaves
Define Electromagnetic Waves
Waves that consist of perpendicular electric and magnetic oscillations. All electromagnetic waves travel at the speed of light in a vacuum.
Define Frequency
The number of waves that pass a point in a unit time period. It is the
inverse of the time period.
Define Fundamental Mode of Vibration
The oscillation of a wave at its natural
frequency
Define Intensity
The power transferred per unit area. It is proportional to the square of a
wave’s amplitude
Define Interference
The superposition of the amplitudes of waves when they meet
Define 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
Define Nodes
A position of minimum displacement in a stationary wave
Define Oscilloscope
A device used to display and analyse waveforms
Define Path Difference
A measure of how far ahead a wave is compared to another
wave, usually expressed in terms of the wavelength.
Define Period
The time taken for a wave to complete one full cycle.
Define Phase Difference
The difference in phase between two points on a wave. It is usually expressed in radians
Define Phase Difference
The difference in phase between two points on a wave. It is usually expressed in radians
Define Polarisation
The restriction of a wave so that it can only oscillate in a single plane. This can only occur for transverse waves
Define Progressive Waves
Waves that transfer energy from one point to another
without a transfer of matter
Define Reflection
The bouncing of a wave at a boundary. The angle of incidence will equal to the angle of reflection
Define Refraction
The changing of speed of a wave as it passes into a new medium. If it passes into an optically denser medium, it will slow down
Define 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
Define Stationary Wave
A wave that stores, but does not transfer, energy.
Define Superposition
When two coherent 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
Define 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
Define Transverse Waves
A wave with oscillations that are perpendicular to the
direction of energy propagation. Electromagnetic waves are examples of transverse waves
Define Wave Speed
The product of a wave’s frequency and wavelength
Define Wavelength
The distance between two identical positions on two adjacent waves. It is commonly measured from peak to peak or trough to trough
Define 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
