2007-08-09 05:51:58 · 5 answers · asked by declan 2 in Science & Mathematics ➔ Physics
It's not 180 degrees...unless you're talking about the fact that the center of the rainbow's circle is always 180 degrees away (i.e. directly opposite) from the direction of the sun.
What you may be thinking of, is the fact that the size of the circle is always the same for all rainbows (about 80 degrees in angular width).
This has to do with the refraction of light, and the shape and composition of water droplets.
Whenever light strikes something transparent (like a water droplet), it bends, and starts traveling at a different angle within the object. The exact amount of the bend depends on the angle at which it struck, and the material of which the object is made. It also depends slightly on the color of the light. Also, when the light travels within the object and then strikes the object's other side, all or part of the light may reflect back (like a mirror), at an angle which depends on the object's shape.
The point is, if you know that the material is water, and you know that the water droplets are shaped like spheres, you can calculate the exact angle at which the light (coming from the sun) will bounce and bend within the droplet before it comes out again.
And it turns out that this angle ranges from about 40 degrees (for blue light) to 42 degrees (for red light).
So, what we see is a bunch of reflected light that is 40 to 42 degrees away from the direction that the sun's light is traveling. This results in a circle whose radius is 40-to-42 degrees, and whose diameter is 80-to-84 degrees.
2007-08-09 05:59:06 · answer #1 · answered by RickB 7 · 2⤊ 1⤋
It has to do with the index of refraction of water which is what rainbows are made of and the position of the light source. You have to draw an optical ray diagram of the source and a droplet of water and use Snell's Law of Refraction. You will find out the that the rainbow actually is a cone of 42 degrees. see ref below for example and color photos
2007-08-09 13:07:07 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Rainbows aren't 180 degress, they are 360 degrees because they are round we only see it as 180 degrees.
2007-08-09 13:25:22 · answer #3 · answered by Anonymous · 0⤊ 0⤋
A rainbow is actually 360 degrees. It's a circle. We only see part of it though because it is blocked (visually of course) by the ground.
2007-08-09 12:56:44 · answer #4 · answered by Anonymous · 1⤊ 0⤋
a rainbow is the result of sunlight falling on the the drops of rainfall and due to the dispersion it creates 360 degree circle!
containing 7 colours!
2007-08-09 13:02:53 · answer #5 · answered by Anonymous · 0⤊ 0⤋