Refraction through a rectangular block (including wave front diagrams)
I can describe what refraction is, draw accurate diagrams of refraction and use the idea of wavefronts to explain what causes refraction.
Refraction through a rectangular block (including wave front diagrams)
I can describe what refraction is, draw accurate diagrams of refraction and use the idea of wavefronts to explain what causes refraction.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- Refraction is when waves travel from one transparent medium to another, causing a change in direction.
- When waves slow down, they turn towards the normal line (angle of incidence > angle of refraction).
- When waves speed up, they turn away from the normal line (angle of incidence < angle of refraction).
- Refraction can be investigated using a clear rectangular block, ray box and narrow slit, pencil, paper and a protractor.
- Refraction occurs when one side of a wavefront enters the new medium before the other, causing a change in wave speed.
Keywords
Refraction - Refraction occurs when waves travel from one transparent medium to another, causing a change in wave speed and direction.
Normal - The normal is an imaginary line drawn at 90° to a surface.
Angle of incidence - The angle of incidence is the angle between the incident ray and the normal.
Angle of refraction - The angle of refraction is the angle between the refracted ray and the normal.
Wavefront - Wavefronts are lines drawn to represent the peaks of a wave.
Common misconception
Pupils sometimes rote-learn what specific examples of refraction look like, rather than developing a more general understanding of the direction waves turn based on changes in wave speed.
Teach pupils the general theory of refraction and apply it to a variety of different examples where wave speed changes (e.g. sound waves refract in the opposite direction to light at an air-glass boundary due to the different wave speeds).
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Starter quiz
6 Questions
loses its brightness as it passes through the object
passes through the object
bounces off the surface of the object
Exit quiz
6 Questions
