Which two colors of light combine to form the color yellow?

Draw a neat diagram to show the refraction of a light ray through a glass prism,and label on it the angle of incidence,and angle of deviation.

$A$ convex lens can be used to correct long-sightedness (hypermetropia).

After passing through the pupil, light rays fall on which part of the eye and undergo refraction?

An old person is unable to see clearly nearby objects as well as distant objects. $(i)$ What defect of vision is he suffering from? $(ii)$ What kind of lens will be required to see clearly the nearby as well as distant objects? Give reasons.

$(a)$ Explain how a normal human eye is able to see distinctly objects placed at a distance as well as those placed at a nearer distance.
$(b)$ What are the far point and near point of a normal human eye?