Refraction at a Plane Surface

• What is the refractive index of a material?

  Ratio of light speed in substance to vacuum
• What causes refraction in a wave?

  Change in speed at a boundary
• What is a medium in optics?

  A transparent material
• How does a wavefront change direction during refraction?

  Part of it hits the boundary first
• What are the conditions for refraction?

  • More optically dense medium: slower waves, smaller angle
  • Light bends towards the normal
  • Less optically dense medium: faster waves, larger angle
  • Light bends away from the normal

  
• What is the angle of incidence?

  Angle between incident ray and normal
• What is the angle of refraction?

  Angle between refracted ray and normal
• What determines the amount of refraction?

  Difference between angles of incidence and refraction
• What happens when light passes from a less dense to a more dense medium?

  Light speed decreases and wavelength shortens

  
• What happens when light passes from a more dense to a less dense medium?

  Light speed increases and wavelength lengthens

  
• What remains unchanged when a wave refracts?

  Frequency of the wave
• What occurs when light hits a boundary at 90°?

  Wave passes straight through without direction
• What is the refractive index of air?

  n = 1
• What does a higher refractive index indicate?

  More optically dense material
• How is the refractive index calculated?

  n = $\frac{c}{c'}$
• What does the refractive index represent in terms of units?

  Dimensionless quantity
• What are the examiner tips for understanding refraction?

  • Visualize with a car on mud analogy
  • Check calculations for refractive index > 1
  • Assume n = 1 for air in questions