6.2.4 Refraction Ray Diagrams

• What is refraction?

  Refraction is the bending of light as it passes from one medium into another with a different density.
• Why is understanding refraction important in GCSE Physics?

  Understanding refraction is a key part of GCSE Physics.
• What are the key concepts related to refraction?

  • Normal: A line perpendicular to the boundary at the point of incidence.
  • Incident Ray: The incoming ray striking the boundary.
  • Refracted Ray: The ray that bends as it enters the second medium.
  • Angle of Incidence (\(i\)): Angle between the incident ray and the normal.
  • Angle of Refraction (\(r\)): Angle between the refracted ray and the normal.
• What happens to light when it passes from a less dense medium to a denser medium?

  It slows down and bends towards the normal.
• What happens to light when it passes from a denser medium to a less dense medium?

  It speeds up and bends away from the normal.
• What are the steps to draw a refraction ray diagram?

  1. Draw the boundary between two mediums.

  2. Draw the normal at the point of incidence.

  3. Draw the incident ray approaching the boundary.

  4. Mark the angle of incidence (\(i\)).

  5. Determine the direction of refraction.

  6. Draw the refracted ray.

  7. Mark the angle of refraction (\(r\)).
• How do you determine the direction of refraction when light enters a denser medium?

  You draw the refracted ray bending towards the normal.
• How do you determine the direction of refraction when light exits a denser medium into a less dense medium?

  You draw the refracted ray bending away from the normal.
• What is Snell's Law used for?

  Snell's Law is used to calculate the angles of incidence and refraction quantitatively.
• What is the formula for Snell's Law?

  $n_1 \sin(i) =$$n_2 \sin(r)$
• What do \(n_1\) and \(n_2\) represent in Snell's Law?

  • \(n_1\): Refractive index of the first medium.
  • \(n_2\): Refractive index of the second medium.
• How do convex lenses affect light rays?


  Convex lenses converge light rays.
• How do concave lenses affect light rays?

  Concave lenses diverge light rays.
• What are some optical phenomena caused by refraction?

  • Mirages
  • Light bending through layers of air with different temperatures
• What is the importance of refraction ray diagrams?


  • Visualize how light bends between mediums.
  • Aid in understanding and predicting light behavior.