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What happens to the intensity of light f...

What happens to the intensity of light from a bulb if the distance from the bulb is doubled ? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of LASER beam is responsible for the constant intensity which is missing in the case of light from the bulb ?

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Intensity of waves is inversely proportional to source of distance from source `(because I prop (1)/(r^(2)))` when distance become double then intensity become `(1^(th))/(4)` value they do not spread hence here intensity remains same.
Following geometric characteristics of LASER beam are responsible for constant intensity,
(i) Unidirectional
(ii) Monochromatic
(iii) Coherent light
(iv) Highly collimated
These characteristics are absent in case of bulb in given case.
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