Define Focal Length Of Spherical Lens

(a) Define focal length of a spherical lens. (b) A divergent lens has a focal length of 30 … to show the formation of image in the…

Answers:

(a) Focal length of a spherical lens is defined as the distance between optical center and focus of the lens. 
(b) Given: focal length of concave lens f= -30 cm
Height of the object, h = 5 cm 
Image distance, V = -15 cm 
Applying the lens formula