GCSE Physics

Rear Reflectors

Red plastic reflectors on the back of cars and bikes actually consist of many 45-90-45° prisms. White light shone into them is reflected back towards the source:

close up of red rear reflector with white light totally internally reflecting back towards the source

Since the plastic is red, only red light is transmitted through them. This allows other road users to identify the reflector as being on the back of the bike or car.

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