Refracting light
I can describe and draw how a ray of light refracts when it moves from one medium to another, and explain how refraction can cause virtual images.
Refracting light
I can describe and draw how a ray of light refracts when it moves from one medium to another, and explain how refraction can cause virtual images.
Lesson details
Key learning points
- Light changes direction when it moves into a new medium (material) at an angle to the normal. This is called refraction.
- When light enters a transparent material from air, it turns towards the normal.
- When light leaves a transparent material and re–enters air it turns away from the normal.
- A ray that enters and leaves glass through parallel sides ends up in its original direction, but displaced to the side.
- Refraction can cause virtual images of objects to appear where light seems to be coming from.
Common misconception
A ray of light curves as it passes through glass, perspex or water.
Use a perspex block with the bottom painted white to demonstrate the path of a ray of light through it. Avoid putting too much emphasis on the term 'bending' light, instead try to primarily refer to light changing direction at a boundary.
Keywords
Transmit - when light moves into and through a new medium
Medium - the material that light is travelling through
Refraction - when light changes direction when it enters a new medium
Normal - a line drawn at 90° to the surface of a material
Virtual image - a representation of an object seen where light appears to be coming from, not where light actually comes from
Equipment
Transparent rectangular blocks, ray boxes (and power supplies if needed), coins (or heavy counters), mugs/white plastic cups (or similar open–topped, non–transparent containers), beakers.
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).
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