Waves which do not require a medium to travel through
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Transverse wave
A wave that consists of particles which oscillate perpendicular to the direction of the propagation of the wave
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Longitudinal wave
A wave that consists of particles which oscillate parallel to the direction of the propagation of the wave
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Compression
Area of maximum pressure in a longitudinal wave
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Rarefaction
Area of minimal pressure in a longitudinal wave
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Amplitude, A
Maximum displacement of particles from their mean position, metres
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Period, T
Time taken for one complete oscillation to occur, seconds
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Frequency, f
Number of oscillations per second, hertz
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Wavelength, λ
Distance between corresponding points on successive oscillations of a wave, metres
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Wavefront
A line joining all points in a medium where the waves are in phase
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Phase
Refers to the position within a cycle that the particle occupies relative to the onset of the cycle
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Superposition
When multiple waves of the same type meet at a point, the resultant displacement of the oscillations will be the vector sum of the individual displacements
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Interference
When two sources of waves cause a pattern of maxima and minima
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Path difference
Difference in distance from each source to a particular point
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Constructive superposition
When path difference is 0 or a integer number of wavelengths
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Coherent sources
Same frequency and wavelength and maintain a constant phase relationship
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Standing waves
Created by the superposition of two progressive waves of equal frequency and amplitude moving in opposite directions
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Node
Point of 0 amplitude on a standing wave
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Antinode
Point of maximum amplitude on a standing wave
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Fundamental frequency
Frequency at which a standing wave is formed with one antinode
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Overtones
Notes emitted by vibrations other than the fundamental frequency
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Harmonics
Overtones which have an integer multiples of the fundamental frequency
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Diffraction
When a wave passes through a gap or partially obstructed by a barrier, the wavefront spreads out into the shadow region
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Huygens' construction
Every point on the wavefront considered as a source of secondary wavelets which spread out with wave velocity; the new wavefront is the superposition of the wavelets
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Plane polarised waves
Transverse waves in which the oscillations occur in a single plane
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Pulse echo techniques
Sonar, radar, ultrasound
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Ultrasound
Pulses sent into body and bounce back when there is a change in density (tissue); reflections detected; computer generates an image
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Limitations of pulse echo techniques
Pulse must be emitted for a short time otherwise the detector may confuse the emitted and received pulses
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Refraction
Change in direction of a ray of light passing from one medium to another at an angle
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Law of reflection
Angle of incidence is equal to the angle of reflection
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Refractive index
Ratio of the speed in medium 1 to speed in medium 2
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Critical angle
Angle of incidence which causes refraction at 90°, above which total internal reflection occurs
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Critical angle equation
Sin C = 1/n
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Focal point
Point where parallel rays of light meet or appear to diverge from
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Converging lens
Forms a real image where the light rays meet
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Diverging lens
Forms a virtual image where no rays intersect
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Power of a lens
Refers to the ability of the lens to deviate rays of light through large angles, measured in dioptres
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Focal length
Distance between optical centre of lens and focal point
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u
Object distance
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v
Image distance
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f
Focal length
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Other cards in this set
Card 2
Front
Waves which do not require a medium to travel through
Back
Electromagnetic waves
Card 3
Front
A wave that consists of particles which oscillate perpendicular to the direction of the propagation of the wave
Back
Card 4
Front
A wave that consists of particles which oscillate parallel to the direction of the propagation of the wave
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