Exam 2 Flashcards
wave
a traveling disturbance that carries energy from one place to another without requiring matter to travel across the intervening distance
wavelength
the distance between adjacent wave crests, the highest points of adjacent waves
frequency
the number of wave crests that go by a given point every second. a wave completing one cycle has a frequency of one hertz.
hertz (Hz)
the unit of measurement for the frequency of waves; one wave cycle per second
interference
when waves from two diff sources come together at a single point, they interfere with each other.
electromagnetic wave/ radiation
a form of radiant energy that reacts with matter by being transmitted, absorbed, or scattered. A self-propagating wave made up of electric and magnetic fields fluctuating together. A wave created when electrical charges accelerate, but requiring no medium for transfer.
light
a form of EM wave to which the human eye is sensitive. Light travels at a constant speed (c) and it needs no medium to travel.
speed of light (c)
the velocity at which all EM waves travel, regardless of their wavelength or frequency; equal to 300 million m/sec
Doppler Effect
the change in frequency of wavelength of a wave detected by an observer bc the source of the wave is moving
transmission
one of three responses of an EM wave encountering matter, in which light energy passes through the matter unaffected (light transmits through glass)
refraction
a response of an EM wave to matter, in which the wave slows down and alters direction
absorption
one of three possible responses of an EM wave encountering matter, in which light energy is converted into some other form, usually heat energy
diffuse scattering
a process by which light waves are absorbed and reemitted in all directions by a medium such as clouds or snow
Electromagnetic spectrum
the entire array of waves, varying in frequency and wavelength, but all resulting from an accelerating electrical charge; includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays, and others
radio waves
part of the EM spectrum that ranges from the longest waves–wavelengths linger that Earth’s diameter–to waves a few meters long
microwaves
EM waves, with wavelengths ranging from apprx. 1 meter to 1 millimeter, which are used extensively for line-of-sight communications and cooking
infrared radiation
wavelengths of electromagnetic radiation that extend from a millimeter to a micron; felt as heat radiation
visible light
EM waves with a wavelength that can be interpreted by nerve receptors in the brain and seen as color; wavelengths range from 700 nanometers for red light to 400 nanometers for violet light
X-ray
high-frequency and high-energy EM waves that range in wavelength from 100 nanometers to 0.1 nanometer, used in medicine and industry
Gamma ray
the highest energy wave of the EM spectrum with wavelengths less than the size of an atom, less than one-trillionth of a meter; normally emitted in very high-energy nuclear particle reactions
frames of reference
the physical surroundings from which a person observes and measures the world
theory of relativity
the idea that the laws of nature are the same in all frames of reference. Einstein divided his theory into 2 parts- special and general relativity
special relativity
refers to things moving at a constant speed; deals with reference frames that do not accelerate
general relativity
refers to anything moving regardless of velocity