KS5 Waves

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Wave & Optics - Objectives


• Progressive waves

• Transverse waves

• Longitudinal waves

• Polarisation

• Interference

• Standing waves

• Refraction of light

• Total internal reflection

Learning Outcomes

Students should know about:

  • Oscillation of the particles of the medium; definitions of:
    • amplitude
    • frequency
    • wavelength
    • speed
    • phase
    • phase difference (in radians, degrees or fractions of a cycle)
  • c = fλ
  • f = 1/T
  • Characteristics and examples of longitudinal and transverse waves, including sound, electromagnetic waves and waves on a string.
  • the direction of displacement of particles/fields relative to the direction of energy propagation.
  • Electromagnetic waves all travel at the same speed in a vacuum.
  • Polarisation as evidence for the nature of transverse waves; applications e.g. Polaroid sunglasses, aerial alignment for transmitter and receiver.
  • The formation of stationary waves by two waves of the same frequency travelling in opposite directions; no mathematical treatment required but graphical explanation is expected.
  • Simple graphical representation of stationary waves, nodes and antinodes on strings.
  • f = 1/2L x (√ T/μ) for the first harmonic (fundamental)
  • Stationary waves formed on a string and those produced with microwaves and sound waves.
  • The terms fundamental and overtone will not be used.
  • Refractive index of a substance s , ns = c/cs; Candidates are not expected to recall methods for determining refractive indices
  • The refractive index of air being approximately 1
  • Snell's Law of refraction for a boundary between two different substances of refractive indices n1 and n2 in the form:
    n1sin θ1 = n2sin θ2
  • Total internal reflection including calculations of the critical angle θc at a boundary between a substance of refractive index n1 and a substance of lesser refractive index n2 or air:
    sin θc = n2/ n1
  • Simple treatment of fibre optics including function of the cladding with lower refractive index around central core limited to step index only; application to communications.
  • Material and modal dispersion
  • the principles and consequences of pulse broadening and absorption
  • REQUIRED PRACTICAL - investigation into the variation of the frequency of stationary waves on a string with length, tension and mass per unit length of the string.

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