Refraction of Waves

• What should higher tier students be able to use to explain refraction?

  Wavefront diagrams
• What happens to light as it passes through water?

  It appears to change direction
• What is a key fact about refraction?

  Waves change direction when they change speed
• How can refraction be illustrated?

  With a ray diagram
• What happens to light when it passes from air into glass?

  Its velocity decreases
• What does the normal represent in a ray diagram?

  A line at right angles to the surface
• What occurs when waves slow down?

  They bend towards the normal
• What happens when light waves pass from glass back to air?

  Their velocity increases
• What occurs when waves speed up?

  They bend away from the normal
• What can cause the image of an object to appear shifted?

  Refraction of light waves
• When does refraction not occur?

  When waves enter at right angles
• What is a wavefront?

  An imaginary line connecting points in waves
• How can wavefronts help visualize waves?

  They show lots of waves moving together
• What happens to wavefronts when they enter a new medium?

  Parts of the wavefront slow down
• What occurs to the wavelength as wavefronts slow down?

  The wavelength gets smaller
• What is the result of wavefronts getting closer together?

  Waves change direction towards the normal
• What happens when wavefronts approach along the normal?

  The whole wavefront slows down simultaneously
• What is the outcome when the whole wavefront slows down?

  Waves do not change direction
• What are the key concepts of refraction?

  • Waves change direction when speed changes
  • Light slows down in denser mediums
  • Light bends towards the normal when slowing down
  • Light bends away from the normal when speeding up
  • Refraction does not occur at right angles
• What are wavefronts and their significance?

  • Imaginary lines connecting points in waves
  • Help visualize multiple waves moving together
  • Show changes in direction during refraction