# 4.4 Waves Definitions

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• Created by: Tom466
• Created on: 14-12-22 22:27
Amplitude
The maximum displacement of a wave from the equilibrium position
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Antinode
The point of maximum amplitude on a stationary wave
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Coherent
Two waves are coherent if they have a constant phase relationship
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Compression
An area of high pressure and density on a longitudinal wave
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Constructive
Interference of two waves that are in phase
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Critical Angle
The angle of incedence at a boundary that produces and angle of refraction of 90 degrees
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Destructive
Interference of two waves that are out of phase
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Diffraction
The spreading out of waves as they pass through a gap, or arround an object, with a size similar to the wavelength of the wave
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Displacement
The distance from the equilibrium of any point along a wave
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Electromagnetic wave
A wave of oscillating electric and magnetic field. They all travel at the speed of light through a vacuum
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Frequency
The number of oscillations per second
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Fundamental
The lowest frequency harmonic of a stationary wave
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Hertz (Hz)
The unit of frequency. 1Hz = 1 complete oscillation per second
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Intensity
The power per unit area perpendicular to the direction of wave propagation. Proportional to the amplitude of the wave squared
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Interference
When two waves meet at a point, the displacement of the resultant is the sum of the displacements of the two original waves that causes a fixed pattern
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Longitudinal
Waves that oscillate parallel to the direction of wave propagation. The can't be polarised
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Monochromatic
Electromagnetic waves of a single frequency
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Node
A point of zero amplitude on a stationary wave
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Oscillation
A motion back and forth about an equilibrium position
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Path Differance
The difference in length of two paths taken by coherent waves. If the path difference is a whole number of wavelengths, they will interfere constructively, while an odd number of half wavelengths leads to destructive interference
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Period
The time taken for one complete oscillation of a point on the wave inversely proportional to frequency
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Phase difference
Difference in angle between points on the some wave of similar points on two waves
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Plane polarised
Transverse waves where all oscillations are in a single plane that is perpendicular to the direction of wave propagation
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Progressive wave
A wave that transfers energy from one place to another as a result of oscillations in fields or particles
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Rarefaction
An area of low pressure and density in a longitudinal wave
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Reflection
When waves hit a surface and "bounce" back. The angle of incidence is equal to the angle of reflection
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Refraction
When waves pass from one medium into another, they change speed and direction
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Refractive index
Optical property of materials. The ratio of the speed at which light passes through a vacuum to the speed of light through the material
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Stationary wave
An interference pattern caused by the superposition of two waves of equal frequency and amplitude travelling in opposite directions. The resultant wave is formed of nodes and antinodes. Energy is stored (rather than transferred like in a progressive wave)
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Superposition
When two waves meet at a point, the displacement of the resultant wave is equal to the sum of the displacements of the two original waves
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Total internal reflection
When the angle of incidence is greater than the critical angle, all light is reflected back into the material
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Transverse
Waves that oscillate perpendicular to the direction of wave propagation. They can be polarised
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Wavelength
The distance between two consecutive points on a wave that are in phase with one another
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Wave speed
The distance propagated by a wave in a second - v=fλ
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Snell's law
N1sinθ1 = N2sinθ2

Where N is the refractive index of the material and θ is the angle of incidence or refraction
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## Other cards in this set

### Card 2

#### Front

The point of maximum amplitude on a stationary wave

Antinode

### Card 3

#### Front

Two waves are coherent if they have a constant phase relationship

#### Back ### Card 4

#### Front

An area of high pressure and density on a longitudinal wave

#### Back ### Card 5

#### Front

Interference of two waves that are in phase

#### Back 