Question

what is meant by problems Rider Si units Westindies of lens focal length 40 cm and another of 20 CM write the nature of power of its lens​

Answer 1

Let take lens1 as focal of 40 and lens2 of focal length of- 20 cm and p1 as power of lens1 and p2 as power of lens2

positive sign of lens1 represent it is a convex lens . hence, it is real and invert

similarly lens2 is virtual and erect

p1=100/f (for cm)

p1=2.5D

p2=100/f (for cm)

p2=-5.0D