Chapter 1.14 Nature of waves - Summary Edexcel A Level Physics Student Book 1 - Physics (9PH0)

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
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○ 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




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