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Chapter 18 vocab
Term | Definition |
---|---|
mechanical wave | 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 | 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 a medium are spaced out |
longitudinal wave | wave in which the vibration of the medium is parallel to the direction the wave travels |
surface wave | wave that travels along a surface separating two 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 points |
frequency | the number of complete cycles that pass a point in a given time |
hertz | meters per second that frequency is measured in |
wavelength | the 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 | 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 a larger displacement |
destructive intereference | occurs when two or more waves combine to produce a wave with a smaller displacement |
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 position |
antinode | a point where a crest or trough occurs midway between two nodes |
sound waves | are longitudinal waves |
intensity | the rate at which a wave's energy flows through a given area |
decibal | is 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 listener, or both. |
resonance | the response of a standing wave to another wave of the same frequency |
electromagnetic waves | transverse waves consisting of changing electric fields and changing magnetic fields |
electric field | in a region of space exerts electrical forces on charged particles |
magnetic field | in a region of space produces magnetic forces |
electromagnetic radiation | The transfer of energy by electromagnetic waves traveling through matter or across space |
photoelectric effect | the emission of electrons from a metal caused by light striking |
photons | packets of electromagnetic energy |
intensity | the rate at which a waves energy flows through a given unit of area |
electromagnetic spectrum | The 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 tempurature |
transparent | material that transmits light |
translucent | material that scatters light |
opaque | material that either absorbs or reflects all of the light that strikes it |
image | a copy of an object formed by reflected waves of light |
regular reflection | occurs when parallel light waves strike a surface and reflect all in the same direction |
diffuse reflection | occurs when parallel light eaves strike a rough, uneven surface, and reflect all in the same direction |
mirage | a false or distorted image |
polarized light | light with waves that vibrate in only one plane |
scattering | light is redirected as it passes through a medium |
dispersion | the process in which white light separates into colors |
primary colors | three specific colors that combine in varying amounts to create all possible colors |
secondary color | a combination of two primary colors |
complimentary colors of light | any two colors of light that combine to form white light |
pigment | a material that absorbs some colors of light and reflects others |
complimentary colors of pigment | any two colors of pigments that combine to make black pigment |