Chapter 25
Sine Curve
A curve whose shape represents the crests and troughs of a wave, as traced out by a swinging pendulum that drops a trail of sand over a moving conveyor belt.
Red Shirt
A decrease in the measured frequency of light (or other radiation) from a receding source; called the red shift because the decrease is toward the low-frequency, or red, end of the color spectrum.
Wave
A disturbance that repeats regularly in space and time that is transmitted progressively from one place to the next with no actual transport of matter.
Interference Pattern
A pattern formed by the overlapping of two or more waves that arrive in a region at the same time.
What is an example of a longitudinal wave?
A spring being pulled in and out.
Transverse
A wave at right angles to the direction the wave is traveling.
Longitudinal Wave
A wave in which the vibration is in the same direction as that in which the wave is traveling, rather than at right angles.
How does a wave transfer energy?
A wave transfers energy from the vibration source to the disturbance in a medium.
Constructive Interference
Addition of two or more waves when wave crests overlap to produce a resulting wave of increased amplitude.
Blue Shirt
An increase in the measured frequency of light from an approaching source; called the blue shift because the apparent increase toward the high frequency, or blue, end of the color spectrum.
Vibration
An oscillation, or repeating back and forth motion, about an equilibrium position.
Nodes
Any part of a standing wave that remains stationary.
Destructive Interference
Combination of waves where crests of one wave overlap troughs of another, resulting in a wave of decreased amplitude.
Crests
One of the places in a wave where the wave is highest or the disturbance is greatest.
Troughs
One of the places in a wave where the wave is the lowest, or the disturbance is greatest, in the opposite direction from a crest.
In Phase
Term applied to two or more waves whose crests (and troughs) arrive at a place at the same time, so that their effects reinforce each other.
Out of Phase
Term applied to two waves for which the crest of one wave arrives at a point at the same time that a trough of the second wave arrives. Their effects cancel each other.
Hertz
The SI unit of frequency. One hertz (Hz) is one cycle per second.
Doppler Effect
The apparent change in frequency of a wave due to the motion of the source or of the receiver.
Simple Harmonic Motion
The back-and-forth vibratory motion of a swinging pendulum.
Amplitude
The distance from the midpoint to the maximum (crest) of a wave or, equivalently, from the midpoint to the minimum (trough).
Wavelength
The distance from the top of the crest of a wave to the top of the following crest, or equivalently, the distance between successive identical parts of the wave.
How does the frequency of waves change as a wave source moves?
The frequency of waves are higher when you're close to the wave source. When the wave source moves away, low frequency gets to you.
Frequency
The number of events (cycles, vibrations, oscillations, or any repeated event) per time; measured in hertz (or events per time). Inverse of period.
What does the period of the pendulum depend on?
The period of the pendulum depends only on the length of a pendulum and the acceleration of gravity.
Antinodes
The positions on a standing wave where the largest amplitudes occur.
What is the source of all waves?
The source of all waves is vibrations.
Period
The time required for a pendulum to make one to-and-fro swing. In general, the time required to complete a single cycle.
Standing Wave
Wave in which parts of the wave remain stationary. And the wave appears not to be traveling. The result of interference between an incident (original) wave and a reflected wave.
What causes interference patterns?
Waves from different sources arriving at the same point at the same time.
What are some examples of transverse waves?
Waves of stretched strings of musical instruments, light waves, and radio waves.
At what wavelengths can a standing wave form in a vibrating medium?
When only half a wavelength or a multiple of a half of a wavelength fits exactly into the length of the vibrating material.
How do you calculate the speed of a wave?
wavelength x frequency = velocity (speed)
