Actually rainbow is not in curved shape it is a fully formed circle around the earth. we can see only half of it because we are living on earth and our eye intensity is less  so that we can see only half of the rainbow.
The Brainliest Answer!
Rainbow is formed after the rain when there is sunlight.after the rain the atmosphere contains water droplets and they act as small prisms. when sunlight is passed through it the light will get dispersed into 7 colors of different frequency or wavelength.each drop  seems to be in one color between the angles 40.8° and 42.8° with the centre of the its formed in the form of an arc of a circle or we can say curved in shape
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