How Far Does my torch beam go?

Question

When l shine my torch into the night sky, how far will the beam travel, and is that in a straight line?

great answers some really funny too...the point is that lt could be months after l light my torch and the light could still exist in time as a discreet travelling beam..well l think so

Answer 1

A slightly Zen answer would be if no-one sees the light then did it travel anywhere? A better answer would be the light would continue to travel until all the photons were absorbed by dust or other objects. In theory this could mean some photons would travel forever but unlikely There would be some gravitational lensing so the light wouldn't travel in exactly a straight line but very close

Answer 2

It dpends on the type of night. Light is easily absorbed by the atmosphere and light coming out of a torch comes out in every angle possible. This wide dispersion means very little of the light is actually going straight up and given the absorption of light by the atmosphere probably not far. Light is a form of energy and thus will be absorbed by the air around it. To break through the atmosphere you need a focused pwerful beam to negate absorbtion by the atmosphere.

Answer 3

In physical terms the light will disperse the farther it goes into space, until it disperses to nothing. But just suppose it could carry on past our atmosphere. If you could just imagine the beam of light like a flat disc against a wall. Now project that disc through space. It would take 8 minutes for the disc to reach the sun from when you turned it on. Outside of our solar system we have to use measurements of distances in light years. If you stood in your back yard, the disc would reach Proxima Centaur in about 4.5 years. To the nearest galaxy 2.3 million years!!!. I think the batteries have gone out on your torch.............
Unfortunately you would not possibly be able to see this disc reach across space...by the time it reached the sun it would have spread many millions of miles across... its source so faint you may as well look for a candle against the backdrop of Orion!.
However, if you could constrict the disc it would bend with the laws of physics..following the path of the infinite universe....In the time it has taken the known universe to expand ...ultimately it would take the same relative time to light up the wall from behind you....

Answer 4

It depends on the model - power of bulbs/LED, reflector design, freshness of batteries, etc. It also depends on how you define "beam" ... As a previous answerer said, one way is to shine it on something and look for the spot. You could also define it as how far away the torch could be seen from - which, in the right conditions, can beat a mile.

Answer 5

Depending on the power of your torch most of the light will be scattered and absorbed by the atmospheric dust.
It will eventually emerge from the atmosphere straight only if you point exactly vertical above your head and you are very lucky.

Answer 6

The beam will travel to infinity given enough time, not in a straight line due to the curviture of the earth in relation to the atmosphere.

Answer 7

All torch beams travel in a spiral fashion and disappear after exactly 15 picometers

Answer 8

It depends how big your torch is

but instead of shining it in the sky you could just walk with it then it could go for miles as far as it wanted. of course you might need spare batteries and bulbs if they go.

Answer 9

Sluggy is correct. The light beam is a stream of photons that will go on and on until they hit something that absorbs their energy. Theoretically, there are so many photons in the beam that some will go on for ever.

Answer 10

It will keep going until it hits something. The further it goes the wider the beam will spread and the fainter it will be, but the light will still be there even though it is too faint to be seen.