Consider a person climbing a stair case. The potential energy of the person climbing the stair case increases in a discrete manner through fixed doses of energy. If all the steps are assumed to be of the same height "h", the person acquires a quantum of energy "mgh" each time he goes up by one step. Consequently , his potential energy increases by 1 mgh, 2 mgh, 3 mgh, .......etc. It is not possible to acquire an energy which is a fraction of mgh or of any intermidiate value.

While getting down the steps, a person loses energy in doses of mgh.

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By :-   Dr. A. W. Pangantiwar