physical science chp. 20
Terms
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- lens
- a transparent object that uses the property of refraction to magnify or reduce images
- electromagnetic magnetic waves
- energy in wave form that is capable of traveling through a vacuum: radio waves, microwaves, etc.
- principal focus
- a point through which the rays reflected or refracted from a surface will pass
- mechanical waves
- rhythmic disturbances of a medium: sound waves, water waves, etc.
- constructive interference
- the inphase reinforcement of waves as they pass through each other
- hertz (Hz)
- the unit of frequency; one cycle per second
- frequency
- the number of waves that pass a given point in one second
- beam
- a very large number of individual light waves
- concave mirrors
- a mirror that curves like the inner surface of a sphere
- normal
- an imaginary line drawn perpendicular to the surface of a mirror
- X rays
- electromagnetic waves with frequencies higher than ultraviolet light; strong enough to penetrate body tissues
- transverse wave
- a wave whose vibration is at right angles to the direction in which it is traveling
- amplitude
- the distance that a wave rises or falls from its normal rest position
- microwaves
- electromagnetic waves with wavelengths from 0.3 cm to 30 cm, and with frequencies that range from 10(9) Hz to l0(11) Hz.
- wavelength
- the distance between adjacent troughs or peaks
- subtractive primary colors
- yellow, cyan, and magenta; when they are mixed in various proportions, they absorb all other colors except the one that is reflected. When all three are mixed together, they absorb every color, showing black.
- line spectrum
- a display of the various frequencies of light emitted by a source
- dispersion
- the separation of white light into different-colored light waves
- incandescent
- heated to glowing
- reflected ray
- an outgoing ray (away from the reflecting surface)
- radio waves
- electromagnetic waves with wavelengths between 1 and 10 m long and with frequencies below those of visible light waves
- trough
- the lowest point on a wave
- rays
- representations of the directions of light waves
- plane mirror
- a flat mirror
- longitudinal wave
- a wave whose vibration is in the same direction that it is traveling
- prism
- a triangular block of glass that is used to separate visible light into various colors
- destructive interference
- the out-of-phase cancellation of waves as they pass through each other
- radar
- radio detection and ranging devices that detect objects through the transmission and reflection of microwaves off of surfaces
- incident ray
- an incoming ray (toward the reflecting surface)
- real image
- an image that is produced in front of the plane of a mirror
- crests
- the highest point on a wave
- virtual images
- the images that appear to exist beyone a mirror
- gamma rays
- a form of radiation consisting of high-energy electromagnetic waves; electromagnetic waves that originate in the nucleus of an atom; the type of electromagnetic waves with the highest frequencies
- angle of reflection
- the angle between the reflected ray and the normal
- visible light
- electromagnetic waves with wavelengths ranging from 4 x 10(-1) cm to 7 x 10(-5) cm, and with frequencies ranging from 4.5 x 10(14) Hz to 7.5 x 10(14) Hz; the portion of radiant energy that can be sensed by our eyes
- ultraviolet light
- electromagnetic waves that are just beyond visible light in frequency
- velocity
- the rate at which an object changes position in a specified direction
- candela
- the metric unit of light intensity
- additive primary colors
- red, green, blue; form various colors when mixed in different proportions. When all three are mixed, they reflect white
- infrared waves
- electromagnetic waves with frequencies lower than visible light but greater than radio waves
- focal length
- the distance from a lens to its principal focus
- intensity
- the measure of how bright the light from a light source is or the loudiness of sound
- angle of incidence
- the angle between the incident ray and the normal
- law of reflection
- the angle of incidence must be equal to the angle of reflection
- refraction
- the bending of waves as they pass from one medium into another