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Chp17+18Vocab_Ernst
Term | Definition |
---|---|
mechanical wave | disturbance in matter that carries energy from one place to another |
medium | material through which waves travel |
crest | highest point of the wave |
trough | lowest point of the wave |
transverse wave | a wave that causes the medium to vibrate at right angles to the direction in which the wave travels |
compression | area where particles in a medium are spaced close together |
rarefaction | area where particles in a medium are spread out |
longitudinal wave | a wave in which the vibration of the medium is parallel to the direction the waves travel |
surface wave | a wave that travels along a surface separating two media |
periodic motion | motion that repeats at regular time intervals |
period | time required for one cycle, a complete motion that returns to its starting point |
frequency | the number of complete cycles in a given time |
hertz | unit of frequency |
wavelength | the distance between a point on one wave and the same point on the next cycle of waves |
amplitude | the maximum displacement of the medium from it's rest position |
reflection | occurs when a wave bounces off a surface that it cant pass through |
refraction | the bending of a wave as it enters a new medium at an angle |
diffraction | the 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 larger displacement |
destructive interference | occurs when two or more wave combine to produce a wave with smaller displacements |
standing wave | a wave that appears to stay in one place |
node | a point on a standing wave that has no displacement from the rest point |
antinode | a point where the crest or trough occurs midway between two nodes |
electromagnetic waves | transverse waves consisting of changing electric fields and changing magnetic fields |
electric field | a region of space exerts electric forces on charged particles |
magnetic field | a region of space produces magnetic forces |
electromagnetic radiation | transfer of energy by electromagnetic waves traveling through matter |
photoelectric effect | the emission of electrons from a metal caused by light striking the metal |
photons | packets of electromagnetic energy |
intensity | the rate at which a waves energy flows through a given unit of area |
electromagnetic spectrum | a full range of frequencies of electromagnetic radiation |
amplitude modulation | the amplitude of the wave is varied |
frequency modulation | the frequency of the wave is varied |
thermograms | color coded pictures that show variations in temperature |