Assuming a total vaccum. A short layman's explanation would be best.
2006-10-15 21:15:26 · 8 answers · asked by Babyface 3 in Science & Mathematics ➔ Astronomy & Space
The amount of radiation and the square of the distance are inversely related (="inverse square relationship"). Picture a source located at the origin of a sphere (lets say a candle in a dark room). If you stand 1-meter away from it, the total light output from the candle will be spread over an area equal to 4*(Pi)*(Radius)^2 = 1/[4(pi)], where Pi is the ratio between the circles circumference to its diameter (it is equal to 3.14159…). If you stand 2-meters away, the intensity will be 1/[4*(Pi)*(2)^2] = 1/[16(Pi)]. Now, the ratio between these two figures is 4, at 1-meter distance the candle is 4 times brighter than the candle at 2-meters distance, even though the distance has only doubled.
2006-10-15 21:47:46 · answer #1 · answered by q80_demon 1 · 0⤊ 0⤋
Look at light as grains of sand.. Light intensity would then be the density of grain or the number of grains in a constant area...
When light starts off at the source, it is in the form of huge pile.. But as it keeps moving outwards, it spreads around in the form of a circle..
The amount of light/energy is the same.. So this same heap moves out, and forms a thick circle around the centre...
As it keeps moving outwards, re-arrange the sand into a bigger circle... You will notice, that the sand will keep getting lighter, with the sand grains more and more wide spread... The "intensity" of the sand reduces as you go away from the source..
2006-10-15 21:29:52 · answer #2 · answered by Kidambi A 3 · 0⤊ 0⤋
It doesn't always. If it passes through a convex lens, it will focus and its intensity will increase until it passes the focal point.
If it is a collimated beam, such as from a laser, it will not diminish. Otherwise, it will diminish because it spreads out.
You'll never find a perfect vacuum, so some light will always be absorbed or reflected by something.
2006-10-15 21:21:32 · answer #3 · answered by Frank N 7 · 0⤊ 0⤋
picture two circles, one inside the other, with the same center. Draw it if you have to. Imagine that the same amount of light is hitting both of those circles - as if the center is a lightbulb. The inside circle is going to have more light per inch - it has a smaller circumference, so the light is spread more densely. Now look at the bigger circle - it has a bigger circumference, so the light per inch is smaller. The "light per inch" is just another way of saying brightness, or intensity of light.
2006-10-15 21:20:39 · answer #4 · answered by dr. obvious 2 · 0⤊ 0⤋
Any form of energy dissipates when it works. Light rays have to work to reach further and further. Therefore the intensity reduces as the intermediate space increases.
2006-10-15 23:28:07 · answer #5 · answered by Nagaraja M 1 · 0⤊ 0⤋
The same amount of light has to cover more territory the further out you go, so there's not as much per square meter as you get further away.
2006-10-16 02:09:02 · answer #6 · answered by Nomadd 7 · 0⤊ 0⤋
This wikipedia says it all mush better than I can.
http://en.wikipedia.org/wiki/Intensity
2006-10-15 22:26:22 · answer #7 · answered by horse 2 · 0⤊ 0⤋
it doesnt dimish. just the futher away you are from the source the more it appears to be getting less bright due to your eyes
2006-10-15 21:19:39 · answer #8 · answered by bigben12222 2 · 0⤊ 3⤋