Sound Waves and Their Properties in GCSE Physics

Waves

Transfer energy without transferring matter.

Wavefront

Line joining points vibrating in phase (e.g. all crests or all troughs).

Wavelength (λ)

Distance between two consecutive wavefronts (or crest to crest).

Frequency (f)

Number of waves passing a point per second (measured in Hz).

Crest (peak)

Highest point of a transverse wave.

Trough

Lowest point of a transverse wave.

Amplitude

Maximum displacement from the rest position - related to energy/loudness.

Wave speed (v)

How fast the wave travels through the medium.

Wave speed equation

v = f × λ where v = wave speed (m/s), f = frequency (Hz), λ = wavelength (m).

Transverse waves

Vibrations are perpendicular to the direction of wave travel.

Longitudinal waves

Vibrations are parallel to the direction of wave travel.

Sound waves

Produced by vibrating sources, such as a tuning fork or vocal cords.

Compressions

Regions of higher pressure, where particles are close together.

Rarefactions

Regions of lower pressure, where particles are spread out.

Audible range for humans

20 Hz to 20,000 Hz (20 kHz).

Speed of sound in air

Approximately 330-350 m/s, depending on temperature.

Measuring Speed of Sound in Air

Calculate speed using: speed = distance / time (total distance = 2 × measured distance).

Effects of Amplitude

Greater amplitude → louder sound.

Effects of Frequency

Higher frequency → higher pitch.

Echoes

The reflection of sound waves from a surface back to the listener.

Ultrasound

Sound with frequency greater than 20 kHz - above human hearing.

Speed of Sound in Different Materials

Fastest in solids, slower in liquids, slowest in gases (like air).

Uses of Ultrasound

Medical scanning, non-destructive testing, sonar (Sound Navigation and Ranging).

Distance calculation for sonar

distance = (speed × time) / 2 (time is for the wave to go and come back).