What color of light is produced when blue and yellow light are superimposed?

$(a)$ What is dispersion of white light? What is the cause of such dispersion? Draw a diagram to show the dispersion of white light by a glass prism.
$(b)$ $A$ glass prism is able to produce a spectrum when white light passes through it,but a glass slab does not produce any spectrum. Explain why this is so.

$A$ person needs a lens of power $-4.5\, D$ for the correction of her vision.
$(a)$ What kind of defect in vision is she suffering from?
$(b)$ What is the focal length of the corrective lens?
$(c)$ What is the nature of the corrective lens?

The peacock blue color is formed by the superposition of which two colors of light?

Which part of the eye controls the amount of light entering the eye?

Name the component of white light that deviates the least and the most while passing through a prism.