Waves and Sound - Vocabulary Flashcards

Vocabulary flashcards covering key terms related to sound, waves, and factors affecting sound speed.

Sound

A form of energy produced by rapidly vibrating objects; detected by the ear via the auditory nerve.

Audible sound

Frequency range from 20 Hz to 20,000 Hz; detectable by the human ear.

Infrasonic sound

Frequency less than 20 Hz; not audible to humans.

Ultrasonic sound

Frequency greater than 20,000 Hz; not audible to humans.

Wave

A disturbance created in a medium that propagates through the medium.

Transverse wave

Particles move perpendicular to the direction of wave propagation (example: light).

Longitudinal wave

Particles move parallel to the direction of wave propagation (example: sound).

Mechanical wave

A wave that requires a medium for propagation.

Electromagnetic wave

A non-mechanical wave that does not require a medium (example: light).

Medium

Substance through which a wave propagates.

Amplitude

Maximum displacement of a medium’s particle from its rest position.

Time period (T)

Time taken by a particle to complete one vibration; measured in seconds.

Frequency (f)

Number of vibrations (or waves) per second; unit: Hz.

Wavelength

Distance between two consecutive crests (or troughs) in a transverse wave; also the distance traveled in one vibration period.

Wave velocity

Distance traveled by a wave in one second; symbol: c; depends on medium’s elasticity and density.

Rarefaction

In a longitudinal wave, region where particles are farther apart than normal (low density/low pressure).

Compression

In a longitudinal wave, region where particles are closer together than normal (high density/high pressure).

Density (sound in gas)

Speed of sound decreases with increased density; v ∝ 1/√density.

Temperature

Speed of sound increases with temperature; v ∝ √temperature (≈0.61 m/s per °C).

Humidity

Higher humidity increases speed of sound; moist air has lower density than dry air.

Wind direction

Speed of sound increases when wind blows in the direction of propagation and decreases when opposite.