1.14 - Nature of waves
● ***Waves: disturbances which transfer energy (& information) through a
medium/space with no mass transfer
● All waves reflect, refract, diffract
● ***Amplitude: maximum displacement between peak of oscillation and equilibrium
position
● ***Frequency (f): number of complete wave oscillations per second
1
○ f=
T ( time period [s])
● ***Period (T): time taken for a wave to complete one oscillation (2πc/360˚)
● ***Speed: v (wave speed [m/s])=f (frequency [ Hz])× λ(wavelength[m])
● ***Wavelength: displacement travelled during 1 complete wave oscillation
● ***Direction of wave propagation = direction of energy transfer
○ Matter does NOT move in direction of wave propagation (eg rubber duck is
NOT moved horizontally by ripples, BUT only bobs up & down)
Mechanical waves
● Generated by vibrating sources (rely on particles)
● ***Require medium for transmission - energy from vibrations transferred to medium,
then transmitted by the particles within it
● Eg sound, ripples, seismic waves (P-waves [longitudinal], S-waves [transverse])
● ***Speed increases with density of material (ie gas < liquid < solid)
Longitudinal waves
●
(source: oscillation, expansion: rarefaction)
● Particles oscillate parallel to direction of propagation of wave
1
● ***Waves: disturbances which transfer energy (& information) through a
medium/space with no mass transfer
● All waves reflect, refract, diffract
● ***Amplitude: maximum displacement between peak of oscillation and equilibrium
position
● ***Frequency (f): number of complete wave oscillations per second
1
○ f=
T ( time period [s])
● ***Period (T): time taken for a wave to complete one oscillation (2πc/360˚)
● ***Speed: v (wave speed [m/s])=f (frequency [ Hz])× λ(wavelength[m])
● ***Wavelength: displacement travelled during 1 complete wave oscillation
● ***Direction of wave propagation = direction of energy transfer
○ Matter does NOT move in direction of wave propagation (eg rubber duck is
NOT moved horizontally by ripples, BUT only bobs up & down)
Mechanical waves
● Generated by vibrating sources (rely on particles)
● ***Require medium for transmission - energy from vibrations transferred to medium,
then transmitted by the particles within it
● Eg sound, ripples, seismic waves (P-waves [longitudinal], S-waves [transverse])
● ***Speed increases with density of material (ie gas < liquid < solid)
Longitudinal waves
●
(source: oscillation, expansion: rarefaction)
● Particles oscillate parallel to direction of propagation of wave
1
