Question

A planoconcave lens is placed on a paper on which a flower is drawn. How far above its actual position does the flower appear to be –

• A. 10 cm
• B. 15 cm
• C. 50 cm
• D. None of these

Answer 1

Answer: (A)

10 cm

Answer 2

Considering refraction at the curved surface.

u = –20 ; µ₂ = 1

µ₁ = 3/2 ; R = + 20

applying – $\frac { \mu _ { 1 } } { \mathrm { u } }$ =

Ž

i.e. 10 cm below the curved surface or 10 cm above the actual position of flower.