The room is is square with no openings and the mirrored surface is a perfect reflective surface. I would turn on the light and then turn it off. Would the beam keep reflecting from surface to surface? And if not, what would happen to it?
2006-12-21 13:38:10 · 6 answers · asked by cal w 1 in Science & Mathematics ➔ Physics
Let's say that you have a room as you describe. The flashlight points in through a small opening. The opening is covered by a small movable mirror. When the mirror is in place, it is as if that wall was just as perfect as the other five faces. Let us say that the flahlight is pointed as some random direction.
Let us say that the room is 3 m x 3 m x 3 m. There is nothing in the room that absorbs light (You are outside, with your flashlight, with a remote control for the opening; the room has no air -- perfect vacuum)
For our visualisation, let us imagine that you are able to open and close the opening so fast that it only opens for 10 nanosecond (10^-8 second). Then the light beam measures 3 m. It will bounce around the room, not being absorbed nor refracted by anything.
When the front of the beam arrives at a mirror, it bounces with an angle equal to the angle of incidence and starts off for another mirror. After 10 nanoseconds, the entire 3 m of the beam has finished bouncing off the mirror.
With time (very little of it), the beam will get wider (a flashlight beam is not coherent: the photon courses are not parallel) until it fills the entire width of the room and the sides of the beam starts bouncing off the mirrors (in addition to the bouncing of the beam itself). The "length" of the beam is still 3 m.
However, perfect mirrors do not exist. As far as I can tell, the photon that gets reflected is not the same photon. Viewed as a particle, as it bounces off the mirror, it must push against the mirror and cause a push on that wall. This means that the interaction is not instantaneous, some infinitesimal measure of time must be spent bouncing.
2006-12-21 14:02:41 · answer #1 · answered by Raymond 7 · 0⤊ 0⤋
If the room was completely empty and the mirrors were perfect, it should kept bouncing around forever. However, since even the best mirrors we can make are not perfect, each time the beam hits a wall, it will loose a little energy. Since the light travels so blasted quickly, in a 10 ft square cube, it would reflect about 100 million times in a second, it will dissipate so quickly that if you could observe it would appear instantaneous. A beam striking a mirror that is 99.99% reflective would lose 99% of its instensity after 990,000 reflections which would take 1/100 seconds which would appear instantaneous unless you were using high speed timing devices.
2006-12-21 14:10:01 · answer #2 · answered by BB 1 · 0⤊ 0⤋
The beam of light would bounce off each mirror. It would not reflect.
2006-12-21 13:40:44 · answer #3 · answered by amandameibeyer 4 · 0⤊ 0⤋
Well, it should keep reflecting from surface to surface...if you kept the light on. Otherwise, it would probably fade away, because it would eventually hit you.
2006-12-21 13:40:43 · answer #4 · answered by Dynamite 4 · 0⤊ 1⤋
It would eventually be reabsorbed either by you, your clothes, your eyes...etc, or the element in the flashlight that generated the light.
2006-12-21 13:41:13 · answer #5 · answered by xaviar_onasis 5 · 0⤊ 0⤋
i keep asking this question, but nobody knows
2006-12-21 13:45:44 · answer #6 · answered by Fall Out at the Disco 2 · 0⤊ 0⤋