Chapter 9 and 10

Waves

Def: A disturbance that propagates through space, transferring energy with it but no matter

Transverse waves

They travel in a direction perpendicular to the direction of the vibrations

Eg: Water waves

Longitudinal waves

They travel in a direction parallel to the direction of the vibrations

Eg: Sound waves

Only sound is a longitudinal wave

Crests and troughs

Highest and lowest points of a wave

Amplitude

Distance from the Central or rest position and either the lowest or highest points of the wave

Wavelength

Distance between two crests or troughs

Frequency

Number of crests that pass a point per second

Measured in Metres(m)

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Number of complete waves generated per second

Period

Time taken to generate one complete wave

Time taken for crests or waves to complete one wavelength

Formula

Period of Vibration(T) = 1/Frequency of vibrations(Hz)

Wavelength (The distance between two compressions or rarefactions)

Wavefronts

Def: A line that joins all the peaks of a wave or all identical points on a wave

Direction of travel of waves are always perpendicular to the wavefront

Formula: Velocity = Frequency x The distance between two crests or troughs(λ)

Compression (Region of higher pressure)

Rarefaction (Region of lower pressure)

Travels fastest in solid and slowest in gas

Why?

As particles are closely packed, sound energy can be transferred from one particle to another at a faster rate

Amplitude-Loudness

Frequency-Pitch

Larger amplitude-more louder

Higher frequency-higher pitch

How is sound useful?

Echolocation for Bats and dolphins to locate prey

SONAR Technology for boats to know the distance of a shoal of fish underwater