Physics Waves Quiz

Study Notes

Waves transmit energy through space and time.
A repeating back-and-forth motion around an equilibrium position is a vibration.
A disturbance that's progressively transmitted from one place to the next without matter transport is a wave. Light and sound are examples.

The period of a pendulum depends only on its length and the acceleration of gravity.
Mass has no effect on the period.
Two pendulums of the same length have the same period regardless of mass.
A longer pendulum has a longer period than a shorter one; it swings more slowly.
Animals with longer legs have a slower stride than shorter-legged animals.

All waves originate from something vibrating.
The back-and-forth vibratory motion is called oscillatory motion or simple harmonic motion.
A sine curve graphically represents a wave.
High points on a wave are crests; low points are troughs.
Amplitude refers to the distance between the midpoint and a crest (or trough) of a wave. Maximum displacement from equilibrium is amplitude.
Wavelength is the distance between any two identical points (e.g., crest-to-crest). Units for wavelength can be meters, centimeters, or billionths of a meter, depending on the wave.
Frequency is the number of vibrations in a unit of time (typically one second).
Hertz (Hz) is the unit of frequency.
Kilohertz (kHz), megahertz (MHz), and gigahertz (GHz) are higher frequency units.
The frequency of the vibrating source equals the wave's frequency.
Frequency and period are inverses of each other. (frequency=1/period, period=1/frequency).

Energy transfer in a wave involves a medium disturbance, not matter transfer between two points.
Sound waves, like waves in a stretched rope or water, are disturbances in the medium. Particles oscillate, but the medium itself doesn't physically travel.
The Sears Tower in Chicago vibrates at a frequency of approximately 0.1 Hz, meaning its period is 10 seconds.

Wave speed equals wavelength times frequency.
Wave speed depends on the medium through which the wave moves.
In air, the product of wavelength and frequency is the same for every sound frequency. Thus, high and low notes in a chord are heard at the same time.
Long wavelengths have low frequencies, short wavelengths have high frequencies

Waves in stretched strings and electromagnetic waves (light and radio waves) are transverse.
The medium's motion is perpendicular to the wave's direction of travel.

Interference patterns result from overlapping waves from different sources.
In constructive interference, wave effects add together, increasing amplitude.
In destructive interference, wave effects cancel each other out,reducing amplitude to zero (in some areas)
Interference is characteristic of all types of waves.

Standing waves form when waves of same amplitude and wavelength in opposite directions combine.
Nodes are stationary points, antinodes have maximum amplitude.
They can be produced by multiple frequencies, doubling or tripling frequency.
Standing waves are not constantly moving but appear stationary.

The observed frequency of a wave changes if the source (or the observer) is moving.
As a source moves toward an observer, they perceive a higher frequency; as a source moves away, they perceive a lower frequency.
This effect is due to the change in the path length successive waves must travel.
This change in frequency is called the Doppler effect
The effect produces a change in pitch (for sound) as a source approaches or recedes.
Radar uses the Doppler effect to measure speeds.
The Doppler effect applies to light waves, with shifts to the blue (higher frequency) or red (lower frequency) end of the light spectrum.

Bow waves occur when a source travels faster than the speed of the waves it produces.
Wave crests overlap and form a V-shaped bow wave behind the object.
This applies to water waves created by a boat and the sonic booms created by supersonic aircraft.

Shock waves form when an object moves faster than the speed of sound
Pressure waves create a conical shape that extends in all directions behind a supersonic aircraft.
The sonic boom is a strong pressure wave heard when a shock wave reaches a listener.