A simple question on the property of light

  • #1

Main Question or Discussion Point

A light source emits light in all directions, and the light travels at light speed, yet when we shut off this light source, all the light rays immediately disappear. I just thought about this and it just seems so strange. When we think of a sound source, we can shut off the sound source but the sound already emitted would keep travelling and echoing. But what about light, when the light source is turned off, what happens to the photons, how can the light already emitted just disappear?
 

Answers and Replies

  • #2
mathman
Science Advisor
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One difference between light and sound is the speed. Sound in air travels about 1000 ft./sec., while light goes around 186000 miles/sec. You can hear the sound echoes because of the time it takes to die off, while for light the die off is essentially instantaneous.
 
  • #3
ok there's just so much I don't know: what makes light give off light?
 
  • #4
1
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wow That question is more than just a simple question! Nice!
 

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