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Concave Mirrors: Uses

Basically, they are used any time you want to make something’s reflection look bigger... they are magnifying mirrirs!

In a shaving mirror or makeup mirror your reflection is larger so that you can perform 'personal grooming' to a high standard.

Concave reflectors are used in car headlights. The bulb of the head light is placed at the focal point of the reflector. The reflected light emerges in a parallel beam and gives more concentrated visibility to the driver at night.

Concave mirrors are used in solar powered gadgets. The parallel rays of the sun are reflected to focus at the focal point F. The solar energy concentrated at F is then used (usually the IR is used - heat focus) or converted (for example into electrical energy by a solar cell) by the gadget

Historical Footnote

It has been said that Archimedes used a large array of mirrors to burn Roman ships during an attack on Syracuse .

This has never been proved or disproved; however on a popular Discovery Channel show, MythBusters, a team tried to recreate the famous "Archimedes Death Ray".

They were successful at starting a fire on a ship at 75 feet away, however, previous attempts to light the boat on fire using only the bronze mirrors available in Archimedes' time were unsuccessful, and the time taken to ignite the craft would have made its use impractical, resulting in the MythBusters team deciding that the myth was just a myth!