When I turn the light on in my room, it emits photons. Is it a continuous stream of photons travelling at the speed of light? Why can’t there be ‘too much light’?
Let’s say i imagine the lightbulb is a garden hose with water coming out (photons). Why doesn’t the lit up surface the photons reflect off of get wet (saturated)?
When I look at a wall in a lit up room, do those photons travel to my eyes?
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The photons are constantly being absorbed or reflected. The reflected photons are what you see, entering your eyes. The absorbed photons transfer their energy to the wall, heating it up ever so slightly.
For the same reason that when you turn off the lightbulb, it gets dark:
The light is absorbed.
Let’s say that the walls reflect 90% of the light (very reflective!), and let’s say the lightbulb emits 10000000000000000000 photons per second, and that the room is a sphere of radius 1 m. A photon would hit the wall every 0.000000001 seconds, and would have a 10% chance of getting absorbed. After every 0.000000001 seconds there would be 10% less light. After every 0.000000007 seconds there would be only half the light. After just 0.0000004 seconds the photons will pretty much be 100% absorbed.
The lightbulb does make the room brighter over time, but because light travels so fast – 300,000km per second – that time is extremely short. As a photon bounces around the room eventually it gets absorbed into something and turns into heat.
When you turn on the light the photons build up in the room in less than a millisecond to the point where things are absorbing them at the same rate as the lightbulb is emitting them.
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