Mirrors exercises

Torch

 
A torch shining a beam of light onto a wall.
The globe in the torch is placed in a very exact position.

The function of the torch is to project a concentrated light beam a long distance. In designing a torch you are given the following :

A convex mirror;
Concave mirror;
A flat piece of glass;
A convex lens of focal length 10cms;
A convex lens of focal length 30cms;
A concave lens of focal length 15cms.
Design the torch so that a glass surface protects the globe from rain.

Draw the ray diagrams for the light that is emitted from the torch.

Click to see the solution.

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Clear section of glass. Cancle on one side of the glass placed equal distance from the glass as the burning candle on the other side. Burning candle on the other side of the glass. Reflected image of flame. Unlit candle Burning candle Clear glass