why the rainbow is in semi circle? why cant be a circle?
it is a full circle, because the perfectly spherical water droplets in the air split the white sunlight into the spectrum which you see as a rainbow. The light comes in at an angle, and then reflects out at an angle. From your perspective on the ground, that angle exsists in a full 360 degree arc - a circle. You only see a semi-circle because either the earth gets in the way of seeing the rest, or because there isn't sufficient water suspended in the atmosphere to see the whole thing.
actually its a whole circle but we see a semicircle coz the water droplets are above us but if u sit an an aeroplane u can see the whole rainbow in the shape of a circle coz there the water droplets are present both above and below the plane
Why it cant be a square or any other polygon???