Question

Define focal length of divergent lens

Answer 1

Focal length is the distance between the center of a convex lens or a concave mirror and the focal point of the lens or mirror the point where parallel rays of a light meet,or converge

Answer 2

when a ray of light incident parllely on the concave lens it appears to diverge away from a point on the principal focus ,this point is called focus and the distance between the focus and optical centre is called focal length