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Mary Russell
Chapter 17 & 18 vocab
Term | Definition |
---|---|
mechanical wave | is a disturbance in matter that carries energy from one place to another |
medium | the material through which a wave travels |
crest | the highest point of a wave above the rest position. |
trough | the lowest point below the rest position |
transverse wave | a wave that causes the medium to vibrate at right angles to the direction in which the wave travels. |
compression | an area where the particles in a medium are spaced close together. |
rarefaction | an area where the particles in the medium are spread out. |
longitudinal wave | is a wave in which the vibration of the medium is parallel to the direction in which the waves travels. |
surface wave | a wave that travels a long surface separating to media. |
periodic motion | any motion that repeats at regular time intervals. |
period | the 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 | frequency is measured in in cycles per second |
wave length | is the distance between a point on one wave and the same point on the next cycle of the wave. |
amplitude | the maximum displacement of the medium from its rest position. |
reflection | occurs when a wave bounces off a surface that it can not pass through. |
refraction | is the bending of the wave as it enters a new medium at an angle. |
diffration | is 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 a larger displacement. |
destructive interference | occurs when two or more waves combine to produce a wave with a smaller displacement. |
standing wave | is a wavr that appears to stay in one place and it does not seem to move through the medium. |
node | a point on standing wave that has no displacement from the rest position. |
antinode | is a point where a crest or trough occurs midway between two nodes. |
electromagnetic waves | are transverse wave consisting of changing electric fields and changing magnetic fields. |
electric field | in a region of space exerts electric forces on charged particles. |
magnetic field | is a region of space produces magnetic forces. |
electromagnetic radiation | behaves sometimes like a wave and sometimes like a stream of particles. |
photoelectric effect | emission of electrons from a metal caused by light striking the metal. |
photons | packets of electromagnetic energy |
intensity | light decreases as photons travel farther from the source. |
electromagnetic spectrum | full range of frequencies of electromagnetic radiation. |
amplitude modulation | the amplitude of the wave is varied. |
frequency modulation | the frequency of a wave is varied. |
thermograms | are color coded pictures that show variations in temperature. |