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)
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