University of St Andrews
School of Physics and Astronomy

7.  Oscillations and Waves

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Associated tutorial questions (St Andrews only)

• Phasors - rotating vector-like qauantitiess whose length is proportional to the amplitude of the oscillation, and whose angle with the x-axis is the phase of the oscillation.
• Driven oscillators - significant oscillation only when the driving force is of the same frequency as the oscillator  (resonance)
• Transverse waves, eg wave on stretched string - particles oscillate perpendicular to the propagation direction of the wave
• Longitudinal waves, eg sound waves - particles oscillate in the same direction as the propagation of the wave
• Mathematical description of a travelling wave (tied in with SHM)   y = A cos(kx - wt + W) for a wave propagating in the +x direction with an amplitude A, an angular frequency w, a phase at position x = 0 and time t = 0 of W, and an angular wave number k = 2 p /l.
• Particle speed and acceleration determined by differentiating y  with respect to time.  Note that particle speed and wave speed are two very different quantities.

Notes: This material is based strongly on the previous lecture on oscillations.   We will come back to the ideas of phasors for describing phenomena in wave optics.

Similar material to that presented in the lectures is available at:-

• Halliday, Resnick, & Walker - Chapters on:-  Oscillations,   Waves-I

Associated tutorial questions (St Andrews only)
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Created by, and copyright of, Bruce Sinclair, University of St Andrews; last modified 18/09/01