Wave motion is the transfer of energy through a medium without the physical transfer of matter. Examples include vibrations in ropes, springs, and ripple tanks.
7.1.2 Terms related to waves:
Displacement: The distance and direction of a point on a wave from its equilibrium position.
Amplitude: The maximum displacement of a wave from its equilibrium position.
Phase difference: The difference in phase between two points on a wave.
Period: The time taken for one complete oscillation or cycle of a wave.
Frequency: The number of complete oscillations or cycles of a wave per unit time.
Wavelength: The distance between two consecutive points in phase on a wave.
Speed: The rate at which a wave propagates through a medium.
The wave equation: v = fλ, where v is the wave speed, f is the frequency, and λ is the wavelength.
7.1.3 Energy and intensity of progressive waves:
Energy is transferred by a progressive wave as it propagates through a medium.
Intensity is the power per unit area carried by a wave and is given by intensity = power/area.
Intensity is proportional to the square of the amplitude of the wave (intensity ∝ amplitude2).
7.2 Transverse and longitudinal waves:
Transverse waves: The displacement of the medium is perpendicular to the direction of wave propagation.
Longitudinal waves: The displacement of the medium is parallel to the direction of wave propagation.
7.3 Doppler effect for sound waves:
The Doppler effect describes the change in frequency observed when a source of sound waves moves relative to a stationary observer.
The observed frequency (fo) is given by fo = fs(v / (v ± vs)), where fs is the source frequency, v is the speed of sound, and vs is the speed of the source relative to the observer.
7.4 Electromagnetic spectrum:
The electromagnetic spectrum includes all electromagnetic waves, which are transverse waves that travel at the speed of light "c" in free space.
The spectrum ranges from radio waves (long wavelength, low frequency) to gamma rays (short wavelength, high frequency).
Visible light falls within the wavelength range of approximately 400-700nm.
7.5 Polarisation:
Polarisation is a phenomenon associated with transverse waves.
Malus's law (I = I0 cos2 θ) describes the intensity of a plane-polarised electromagnetic wave after transmission through one or more polarising filters, where I0 is the initial intensity and θ is the angle between the transmission axis of the filter(s) and the direction of polarisation.