Which of the following colors is not a primary color?

Light rays entering the eye are refracted by the lens and form an image on a specific part of the eye. What is this part called?

The figure below shows a glass prism placed in the minimum deviation position. $A$ ray of monochromatic light is incident on its face $AB$. Copy the diagram and show the refracted and the emergent ray. Mark the angle of deviation. State any two factors on which the angle of deviation depends.

Is the position of a star as seen by us its true position? Justify your answer.

In the case of the human eye,when light rays enter the eye,most of the refraction occurs at the

How does atmospheric refraction take place? Why do stars twinkle,but planets do not?