Tuesday, 8 February 2011


The sun is a primary source of the Earth’s energy.  In fact, the energy to heat us up travels from it at the speed of light, just like the light rays.  This particular energy rays that cause the most heating are called infra-red rays.  These are also light rays but of longer wavelength. Since it is a light ray, it can also be reflected by mirrors. This is where the idea of ‘solar furnace’ comes about, particularly in hotter parts of the world where solar furnace is used, to collect the rays from the sun and focus them on to kettles or cooking pans.


On a sunny day, take a concave mirror outside to heat a spoonful of water.


Take the same concave mirror outside to light a match. It would help better if you first blacken the head of the match with a pencil.


Be very careful in conducting this practical.

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