ASRJC Wave Motion Notes

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 11-1 Additional Notes Topic 11: Wave Motion Content: • Progressive waves • Transverse and longitudinal waves • Polarisation • Determination of frequency and wavelength Learning Outcomes: Candidates should be able to: (a) show an understanding of and use the terms displacement, amplitude, period, frequency, phase difference, wavelength and speed. (b) deduce, from the definitions of speed, frequency and wavelength, the equation v = f. (c) recall and use the equation v = f. (d) show an understanding that energy is transferred due to a progressive wave. (e) recall and use the relationship, intensity  (amplitude)2. (f) show an understanding of and apply the concept that a wave from a point source and travelling without loss of energy obeys an inverse square law to solve problems. (g) analyse and interpret graphical representations of transverse and longitudinal waves. (h) show an understanding that polarisation is a phenomenon associated with transverse waves. (i) recall and use Malus’ law (intensity  cos2 θ) to calculate the amplitude and intensity of a plane polaris ed electromagnetic wave after transmission through a polarising filter. (j) determine the frequency of sound using a calibrated oscilloscope. (k) determine the wavelength of sound using stationary waves. (To be discussed in Superposition)

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 11-2 Additional Notes • The propagation of light and sound are examples of wave phenomena. • Waves originate from a source which is oscillating. These oscillations then spread and bring energy away from the source in the form of waves – the disturbance travels from one region of space to another. • A wave is a means by which energy may be transferred from one place to another as a result of oscillations. This takes place without the physical transfer of any material between the points. Waves can be classified using: • Medium through which the wave travels through: Mechanical or electromagnetic • Motion of waves: Progressive or stationary • Mode of transport: Transverse or longitudinal A.1 Medium through which the wave travels through – Mechanical waves and electromagnetic waves Mechanical waves: • Mechanical waves require a medium to propagate. Examples include: o waves in a slinky coil or a rope o water waves o sound waves o seismic waves which travel along the Earth’s crust during an earthquake Electromagnetic waves • Electromagnetic waves are generally termed “light” but this term includes the entire electromagnetic spectrum (gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, microwaves and radio waves). • All these forms of light travel at a constant speed in a vacuum (c = 3.00 x 108 m s–1) but have different frequencies (different wavelengths). • Electromagnetic waves do not require a medium to travel. Introduction A Classificati