| A | B |
|---|
| mechanical waves | a disturbance in matter that carries energy from one place to another |
| medium | material through which a wave travels |
| trough | lowest point of the wave below the rest position |
| crest | highest point of the wave above the rest position |
| transverse wave | wave that causes the medium to vibrate at right angles to the direction in which the wave travels |
| longitudinal wave | wave in which the vibration of the medium is parallel to the direction the wave travels |
| compression | area where the particles in a medium are spaced close together |
| rarefaction | area where the particles in a medium are spread out |
| surface wave | wave that travels along a surface separating two media |
| periodic motion | any motion that repeats at regular time intervals |
| frequency | number of complete cycles in a given time |
| period | a complete motion that returns to its starting point |
| wavelength | distance between a point on one wave and the same point on the next cycle of the wave |
| amplitude | maximum displacement of the medium from its rest position |
| reflection | occurs when a wave bounces off a surface that it cannot pass through |
| refraction | bending of a wave as it enters a new medium at an angle |
| diffraction | bending of a wave as it moves around an obstacle or passes through a narrow opening |
| interference | occurs when two or more waves overlap and combine together |
| constructive interference | occurs when two or more waves combine to produce a wave with a larger displacement |
| destructive interference | occurs when two or more waves combine to produce a wave with smaller displacements |
| standing wave | a wave that appears to stay in one place |
| node | point on a standing wave that has no displacement from the rest position |
| antinode | a point where a crest or trough occurs midway between two nodes |
| sound waves | longitudinal waves - compressions and rarefactions that travel through a medium |
| intensity | rate at which a wave's energy flows through a given area |
| decibel | a unit that compares the intensity of different sounds |
| loudness | a physical response to the intensity of sound, modified by physical factors |
| pitch | the frequency of a sound as you perceive it |
| sonar | a technique for determining the distance to an object under water |
| doppler effect | a change in sound frequency caused by motion of the sound source, motion of the listener or both |
| resonance | the response of a standing wave to another wave of the same frequency |
| hertz | unit of frequency, measured in cycles per second |
