Can we keep light even after the bulb is switched off? What if the bulb is placed in a fully closed room?

Because all the surfaces in the room (walls, floor, furniture..) don't reflect 100% of the light. They absorb some. When you turn off the light, in that first instant, some of the light reflects off those walls and floor and furniture. In the second instant, the weakend light may reflect again on another part of the room. But the light after that is too weak to notice.

Those two, maybe three reflections happen in billionths of a second, so you won't notice a delay between turning the light off and being in the dark.

It seems that even the telescope mirrors absorb 5% or more of light per reflections, so even in a fully mirrored room, it would still go dark instantly.

Because the walls of the room are not perfectly reflecting. Suppose that light is bouncing back and forth between two walls, 3 meters apart, and the walls are 99% reflective. After just one microsecond, the light will have been reduced to less than 37% of its original value. A few microseconds more, and it will be completely imperceptible.

Remember that light contains photon particles and after you switch off the light emitting object, the photon particles slowly fade due to the fact that their intensity becomes lower. You need a continous stream of photons to keep the intensity of light at a great level. The photons are not absorbed but just lose their intensity. For more answers or a discussion on phsyics space and astronomy visit astrowhiz on Yahoo Groups!

because the photons are absorbed into the materials, usually as heat. If it was a room of ideal mirrors (100% reflection), you could essentially hold light.

and you can get other things to omit held photons. Ever seen glow in the dark stuff?

Yes,but in a 100%refractive closed materials

the light rays gets obsorbed by the materials present in the room i.e. floor, walls, furniture etc

each time it hits something a very small amount is absorbed, but since light travels so fast a tiny bit each time very very quickly becomes all the light.

Light gets absorbed, and it happens very quickly.

thats deep!!!

You would think that it would but maybe somehow light rays die or something so light cant last without producing more?