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35 Cards in this Set
- Front
- Back
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Amplitude |
The maximum displacement of a wave from the equilibrium position. |
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Antinode |
A 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 |
Angle of incidence at a boundary that produces an angle of refraction of 90° |
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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 around an object, with a size similar to the wavelength of the wave. |
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Displacement |
The distance of a point on a wave from the equilibrium position. |
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Electromagnetic wave |
A wave of oscillating perpendicular electric and magnetic fields. They all travel at the speed of light through a vacuum. |
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Frequency |
The number of complete oscillations per second. |
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Fundamental |
The lowest frequency harmonic of a stationary wave. |
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Harmonic |
Stationary wave formed by frequencies which are integer multiples of the fundamental frequency. (Note: Not all multiples are harmonics, but all harmonics are multiples!) |
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Hertz (Hz) |
The unit of frequency. 1Hz = one 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 |
Superposition that causes a fixed pattern (include the definition of superposition for exams!) |
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Longitudinal |
Waves that oscillate parallel to the direction of wave propagation. They cannot 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 |
The motion back and forth about an equilibrium position. |
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Path difference |
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. |
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Phase difference |
Difference in angle between points on the same wave or 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. |
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Rarefraction |
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 per second – v=fλ |
