Light bounces off objects. This is a good thing because it means that you can see stuff. If light strikes a flat mirror it bounces off in a predictable way. In the diagram below you can see a beam of light, P (called the incident ray) striking a reflective surface and being reflected, Q (called the reflected ray). If you take a line at 90 degrees to the mirror (called the normal) then you find that the angle between the incident ray and the normal (called the angle of incidence) and the angle between the reflected ray and the normal (called the angle of reflection) are identical.
If light is striking a curved surface then slightly different rules apply. Like in a hall of mirrors, strange and distorted reflections may be produced. A classic example is the upside down reflection from the bowl of a spoon.
The red line is the path that light takes from the tip of the large arrow – O. It ends up producing a reduced and inverted image at I.
SciShow has a nice explanation for it below (you might want to let it load before you hit play – my video sharing servers are not the fastest!)
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Questions…
- What is the angle of incidence?
- Roughly how fast do photons travel in a vacuum?
- What is the bending effect observed as light travels from one medium to another called?
- What are the three primary colours of light?
- What word describes the scattering of light as it passes through a triangular prism?
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