A concave convex figure lens made of glas `(mu=1.5)` has surface of radii 20 cm and 60 cm. a. Locate the image ofan object placed 80 cm to the left of the lens along the principal axis. B. A similar lens is placed coaxially at distanc of 160 cm right of it. Locate the position of the image.

Explanation

(a) Focal length of lens
`(1)/(f)=((3)/(2)-1)((1)/(20)-(1)/(60))=((1)/(2))((1)/(30))=(1)/(60)`
`(1)/(v)-(1)/(-80)=(1)/(60)implies(1)/(v)=(1)/(60)-(1)/(80)=(1)/(240)`
`v=240cm`
(b) `I_1` acts as object for second lens.
`u=80cm,f'=60cm,v'=?`
`(1)/(v')=(1)/(60)+(1)/(80)=(7)/(240)`
`v'=(240)/(7)cm`
Final image is formed at distance `(240)/(7)` cm right of second lens.