(A) Draw a ray diagram to show the refraction of a ray of light passing through an equilateral glass prism. Mark the angle through which the emergent ray bends from the direction of the incident ray and also name it.

OR

(B) Name the type of lenses required by the persons for the correction of their defect of vision called presbyopia. Write the structure of the lenses commonly used for the correction of this defect giving reason for such designs.

(A) The ray diagram to show the refraction of a ray of light passing through an equilateral glass prism is shown below:

The angle through which the emergent ray bends from the direction of the incident ray is called the angle of deviation.

OR

(B) The type of lenses required by the persons for the correction of their defect of vision called presbyopia is convex lenses. The structure of the lenses commonly used for the correction of this defect is bifocal lenses, which have a convex lens for distant vision and a concave lens for near vision. This design is used because presbyopia is a defect in which the person can see distant objects clearly but cannot see nearby objects distinctly.