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Q & A: force and intensity from light

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Most recent answer: 01/10/2012
Q:
Can light apply a force? Why does the intensity of light diminish when farther away?
- Matthew (age 17)
Rockville MD USA
A:
Certainly light can exert a force. Just search our site for "light pressure momentum" for more info. 

The light intensity must fall off with distance from the source because the same flow of light gets spread out over more and more area. So that leaves less light per area farther away. A lens or reflector on the source can keep the light confined for some distance from the source, but if you go far enough away it will always spread out.

Mike W.

(published on 01/10/2012)

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