Glossary
Amplitude
The maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position. It indicates the intensity or energy of the wave.
Example:
A loud rock concert produces sound waves with a large amplitude, making your eardrums vibrate significantly.
Doppler Effect
The apparent change in frequency and wavelength of a wave as observed by an observer who is in relative motion to the wave source. Frequency appears higher when approaching and lower when receding.
Example:
The pitch of an ambulance siren sounds higher as it approaches you and then drops noticeably lower as it passes and moves away, illustrating the Doppler Effect.
Energy (of a wave)
The capacity of a wave to do work, which is often related to its amplitude and frequency. For mechanical waves, greater amplitude typically means more energy.
Example:
A tsunami carries immense energy, allowing it to cause widespread destruction as it crashes onto shore.
Frequency
The number of complete repetitions or cycles of a wave that pass a given point per unit of time. It is typically measured in Hertz (Hz).
Example:
If a guitar string vibrates 440 times per second, the sound wave it produces has a frequency of 440 Hz, corresponding to the musical note A4.
Period
The time it takes for one complete cycle or repetition of a periodic wave to pass a given point. It is the inverse of the wave's frequency.
Example:
If a pendulum swings back and forth once every 2 seconds, its period is 2 seconds.
Periodic Wave
A wave that repeats its pattern consistently over both time and space. Its characteristics like amplitude, frequency, and wavelength remain constant.
Example:
The ripples created when a raindrop hits a puddle form a periodic wave as they spread outwards, with each ripple following the one before it.
Speed (of a wave)
The rate at which a wave propagates through a medium. It is determined by the product of the wave's frequency and wavelength (v = fλ).
Example:
Light travels at an incredibly high speed in a vacuum, approximately 3 x 10^8 meters per second, which is why we see lightning before we hear thunder.
Wavelength
The spatial period of a periodic wave, representing the distance over which the wave's shape repeats. It is the distance between two consecutive corresponding points on the wave.
Example:
In a slinky stretched across the floor, the distance from one compressed coil to the next compressed coil represents the wavelength of the wave traveling through it.