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Ch. 12 & 13 Vocab
Term | Definition |
---|---|
compression | a region of high molecular density and high air pressure |
rarefaction | a region of lower molecular density and low air pressure |
pitch | the frequency of an audible sound wave determines how high or low we perceive the sound to be |
doppler effect | an observed change in frequency when there's relative motion between the source of waves and an observer |
intensity | the rate at which energy flows through a unit area perpendicular to the direction of wave motion |
decibel | a dimensionless unit that describes the ratio of two intensities of sounds; threshold of hearing is commonly used as the reference intensity |
resonance | a phenomenon that occurs when the frequency of a force applied to a system matches the natural frequency of a system, resulting in a large amplitude of vibration. |
fundamental frequency | the lowest frequency of vibration of a standing wave |
harmonic series | a series of frequencies that includes the fundamental frequency and integral multiples of the fundamental frequency |
timbre | the musical quality of a tone resulting from the combination of harmonics present at different intensities |
beat | the periodic variation in the amplitude of a wave that is the superposition of two waves of slightly different frequencies |
electromagnetic waves | a wave that consists of oscillating electric and magnetic fields, which radiate outward from the source at the speed of light |
reflection | the change in direction of an electromagnetic wave at a surface that causes it to move away from the surface |
angle of incidence | the angle between a ray that strikes a surface and the line perpendicular to that surface at the point of contact |
angle of reflection | the angle formed by the line perpendicular to a surface and the direction in which a reflected ray moves |
virtual image | an image from which light waves appear to diverge, even though they are not actually focused there; a virtual image cannot be projected on a screen |
concave spherical mirror | a mirror whose reflecting surface is a segment of the inside of a sphere |
real image | an image that is formed by the intersection of light rays; a real image can be projected on a screen |
convex spherical mirror | a mirror whose reflecting surface is an outward-curved segment of a sphere |
linear polarization | the alignment of electromagnetic waves in such a way that the vibrations of the electric fields in each of the waves parallel to each other |