Which primary colors produce different shades on a color TV screen?

Which of the following are the primary colours of light?

Which one of the following combinations of source and screen would produce sharpest shadow of an opaque object?

A glass prism splits white light into different colours. This phenomenon is called dispersion of light by prism. Which one of the following statements is correct ?

Which one of the following colours is seen in the middle of a Rainbow?

When a convex lens produces a real image of an object, the minimum distance between the object and image is equal to