20
(a)
(i) Let a parallel beam be the incident from the left on the convex
lens first f1 = 30 cm and u1 = – , give  v1 = + 30 cm This image becomes
a virtual object for the second lens f2 = –20 cm, u 2 = + (30 – 8) cm = +  22 cm which gives,
v2 = – 220 cm