Question

A thick plano convex lens made of crown glass (refractive index 1.5) has a
thickness of 3cm at its centre. The radius of curvature of its curved face is
5cm. An ink mark made at the centre of its plane face, when viewed
normally through the curved face, appears to be at a distance 'x' from the
curved face. Then, x is equal to:
A. 2.1cm
B. 2.3cm
C. 2.5cm
D. 2cm

Answer 1

Answer:

2.5 cm

Explanation:

Radius of curvature, R=-5 cm Object distance, u=-3 cm The refractive indices n1=1.5 (glass), n2=1.0(air) We have, n 2 v − n 1 u = n 2 − n 1 R n2v−n1u=n2−n1R (The Lensmaker's formula) 1 v − 1.5 − 3 = 1 − 1.5 − 5 1v−1.5−3=1−1.thick-plane-convex-lens-made-of-crown-glass-refractive-index-has-thickness-of-cm-its-centre.