Question

2- (a) Define second focus of a concave lens​

Answer 1

Answer:

Second principal focus and secondfocal length : It is a fixed point on theprincipal axis such that the light rays incident parallel to the principal axis, after refraction through the lens, either converge to this point (in convex lens) or appear to diverge from this point (inconcave lens). It is denoted by F2

Answer 2

Answer:

Concave lens representing second focus as F

2

The second focal point for a concave lens is a point

F

2

on the principal axis of the lens such that the rays of light incident parallel to the principal axis,

after refraction from the lens, appear to be diverging from this point.