Physical Science Unit 5
Terms
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- amplitude
- The maximum displacement of a wave's medium from its equilibrium point.
- crest
- The highest point on a wave.
- electromagnetic waves
- Waves formed by rapidly changing electric and magnetic fields and that require no medium.
- equilibrium position
- The position of a medium that's undisturbed; its resting position.
- frequency
- The number of wavelengths that pass by a particular point in space during a one-second interval.
- longitudinal wave
- A wave in which the medium is displaced in a direction parallel to the motion of the wave.
- mechanical waves
- Waves formed by disturbances in a physical medium.
- medium
- Material through which a wave travels.
- period
- The time it takes one complete wavelength to pass a given point.
- periodic wave
- A series of evenly timed disturbances in a medium.
- reciprocal
- A mathematical relationship in which a value, expressed as a fraction, can be turned into the other simply by flipping the fraction.
- speed of a wave
- The speed at which a wave travels.
- surface wave
- A wave that combines transverse and longitudinal motion.
- transverse wave
- A wave in which the medium is displaced in a direction perpendicular to the motion of the wave.
- trough
- The lowest point on a wave.
- wave
- A regular disturbance that moves either through a medium or space.
- wavelength
- The distance between successive compression peaks in a wave.
- wave pulse
- A single disturbance moving through a medium.
- absorption
- The transfer of wave energy into the medium, usually in the form of heat, when a wave reaches a boundary.
- antinodes
- The points of maximum displacement in a standing wave.
- boundary
- The interface between two different media.
- compression wave
- A longitudinal wave that propagates through a series of rarefactions and compressions of the medium.
- compressions
- The higher-pressure (denser) regions of sound waves.
- constructive interference
- When waves interfere to create a new wave amplitude larger than either of the original waves.
- decibel
- A unit used to measure sound intensity, or loudness, using a logarithmic scale based on the powers of 10.
- destructive interference
- When waves interfere to create a new wave amplitude smaller than either of the original waves.
- diffraction
- The change in direction of sound waves as the pass nearby objects and obstacles.
- echo
- The repeated occurrence of a sound, caused by the original sound wave and its reflection reaching the observer at different times.
- fundamental
- A standing wave in a string that has one antinode and zero nodes. It is the loudest-pitched sound of a plucked string.
- harmonics
- The overlapping standing waves of many different frequencies that occur in a string when it's plucked.
- in phase
- When two waves have amplitudes that are in the same direction.
- interference
- The superposition of two or more waves, resulting in a new wave pattern.
- principle of superposition
- When two or more waves meet, the result is a new wave whose amplitude is the sum of the amplitudes of all the individual waves.
- out of phase
- When two waves have amplitudes that are in opposite directions.
- nodes
- The points of minimum, or zero, displacement in a standing wave.
- pitch
- The "highness" or "lowness" of a sound, as directly to and determined by its frequency.
- rarefactions
- The lower-pressure (less dense) regions of sound waves.
- reflection
- The reversal of wave propagation direction when a wave reaches a boundary.
- refraction
- The transmission of a wave across a boundary, during which its frequency remains constant.
- reverberation
- The perceived elongation of a sound when the original sound wave and its reflection from a boundary reach the observer within 0.1 seconds of each other.
- standing wave
- A repeating wave pattern that has some number of stationary nodes and antinodes that can result from interfering waves.
- subsonic
- Slower than the speed of sound in a particular medium.
- supersonic
- Faster than the speed of sound in a particular medium.
- transonic
- Approximately the speed of sound in a particular medium. In air at room temperature, this is about 343 m/s.
- electromagnetic spectrum
- The entire range of electromagnetic radiation, from 0 Hz to more than 10^23 Hz.
- infrared
- Electromagnetic waves with frequency and energy just below the visible light spectrum.
- nanometer
- One billionth of a meter.
- pigment
- A substance used as coloring.
- primary colors
- Colors that aren't made up of any other colors. In pigments, the primary colors are magenta, cyan, and yellow. In light, they're red, green, and blue.
- prism
- A clear piece of glass used to separate white light into colors.
- secondary colors of light
- Colors formed by combining two primary colors of light.
- speed of light
- In a vacuum, the speed of light is 300,000 km/s (186,000 miles per second).
- ultraviolet
- Electromagnetic waves with frequency and energy just above the visible light spectrum.
- visible light
- Electromagnetic radiation having a wavelength between 380 and 750 nanometers.
- angle of incidence
- The angle the incident, or incoming, ray makes with the normal line.
- angle of reflection
- The angle the reflected ray makes with the normal line.
- concave lens
- A lens that's thicker at the edges than it is at the middle.
- concave mirror
- A mirror whose shiny side resembles the interior of a sphere.
- converging lens
- A lens that focuses parallel rays of light down to a single focal point.
- convex lens
- A lens that's thicker at the middle than at the edges.
- convex mirror
- A mirror whose shiny side resembles the exterior of a sphere.
- eyepiece
- In a microscope, the lens through which the observer looks.
- index of refraction
- A number that compares the speed of light in a given material to the speed of light in a vacuum.
- law of reflection
- When light hits a mirror, the angle of reflection equals the angle of incidence.
- law of refraction
- When light travels from a less dense material to a more dense material, it bends toward the normal.
- lens
- A transparent material, often made of glass, that's either thicker at its edge or thicker at its middle.
- microscope
- An optical instrument used for viewing enlarged images of very small objects.
- normal
- A line drawn perpendicular to a mirrored surface.
- objective
- In a microscope, the lens closest to the object being viewed.
- real
- An image, formed in a mirror or a lens, that's inverted and characterized by solid lines drawn on the ray diagram.
- telescope
- An optical instrument used for viewing distant objects.
- virtual
- An image, formed by a mirror or a lens, that's upright and characterized by the presence of dashed lines in the ray diagram.
- wave-particle duality
- The theory that light travels as both a wave and a series of particles at the same time.