Doppler Effect
With sound and ultrasound

• State what the Doppler Effect is for sound and give everyday examples
• Relate the pitch of a sound wave to the frequency of a sound wave, and explain why a sound:
  · increases in pitch when the source of the sound travels towards a listener,
  · and decreases in pitch when it travels away.
• Use the equation :
  
  to calculate the frequency of sound detected by a listener (L) when :
  either the listener or the source (S) is moving
• Describe applications of the Doppler Effect with ultrasound waves in medicine,eg,
  to measure the rate of blood flow or the heart of a foetus in the womb

Colour
Relationship to wavelength and frequency

• Know that each colour is associated with light of a particular frequency
• Use the equation:
  
  to calculate the wavelength of light of a given frequency and vice versa
• Explain why when white light is refracted through a prism it separates into light of different colours by referring to the difference in the speed of light of different frequencies in glass

Addition and Subtraction of Light

• Know that the superposition of red, blue and green light (primary colours produces white light.
• Use colour prediction to make predictions about the colours produced when different coloured light is mixed
• Explain why a TV screen comprises red, green and blue dots
• Know that the subtractive primary colours are magenta, yellow and cyan, and explain how these colours are obtained
• Define complementary colours as two colours which added together give white
• Determine the complementary colours for red, green and blue

• Explain what determines the colour of an opaque object and of a transparent object when illuminated with white light
• Explain that pigments give an object its colour by absorbing certain frequencies of light and reflecting other frequencies
  · for example, a red pigment reflects red light and absorbs cyan (blue and green)
• Use the concept of colour subtraction to predict how paints can create any colour by using varying amounts of the three primary colours of paint
  · (cyan, magenta, yellow)

• Define a wavefront as an imaginary line that connects waves that are in phase, eg.
  · all at the crest of their cycle
• State Huygens Principal
• define diffraction as the ability of a wave to spread out in wavefronts as they pass through a small aperture or around a sharp edge
• Apply Huygens Principal to explain diffraction qualitatively.
  · Light and dark areas can be described in terms of constructive and destructive interference of secondary waves
• Sketch the diffraction pattern for a single slit
• Use
  
  for a slit of width a to calculate the position (angle) of the dark bands in a single slit diffraction pattern, where:
  

Interference
(special kind of superposition)

• Define interference as when two waves pass through the same region of space at the same time, resulting in superposition of waves
• Explain the concepts of constructive and destructive interference
• Predict areas of constructive and destructive interference from a diagram/source material
• Investigate the interference of waves from two coherent sources vibrating in phase eg:
  · light waves from a double slit
• Draw an interference pattern marking nodal lines and noting positions of maximum interference eg:
  · interference pattern for a double slit