a rainbow actually is a circular ring of colours. we can view only a part of it(arch) from ground level. if we view it from a higher elevation then may be we'll be able to see the full circle.

 

i donno y it is circular, may be because of the rain drops suspended in the air

 

 

Hey vasanth !

How can u say that a rainbow is a 'circular ring of colours' . Why cant it be of any other shape ?????

U must hav read about the formation of rainbow by dispersion of light from tiny droplets acting as prisms . But this does not explain its shape ????

Think about it !

Is there any expert who can provide me with the solution of this question ?????

I would be very thankful !

Hey Umang, I think:

Though I dont exactly know the shape of rainbow, still it appears in the form of a ring cos water drops act as a prism and u know that when u view an object from a prism, only at certain angles, u get a clear vision of the object.At the rest of the angles, the object may be partially visible or may not be visible at all. The same applies with the rainbow.When u look from ur position, it looks like a half ring and u try to go too close to it (say by a plane!) and it won't be visible at all!!

its because the raindrops are spherical

the optical phenomenon that take place ( it requires ray diagram to explain ) after the ray enters the drop is total internal reflection and then the ray comes out

also it has got something to do with the angle between the sun and the rain drop which we will study during engineering

also, obviously the sun has to be behind the observer's eye so that the eye is between the sun and the drop