Question

A glass dumbbell of length $50$ cm refractive index $1.5$ has ends of $5$ cm radius of curvature. The position of the image formed due to refraction at one end only, when a point object is situated in the air at a distance of $20$ cm from the end of the dumbbell along the axis is

• A. 30 cm
• B. 15 cm
• C. 10 cm
• D. 5 cm

Answer 1

The correct option is A 30 cm

Given :- u = -20cm & R = 5m

$\mu =3/2$

Since, $\frac{\mu }{v}-\frac{1}{u}=\frac{\mu -1}{R}$

$\frac{3}{2v}+\frac{1}{20}=\frac{1}{2\times 5}$

$\frac{3}{2v}=\frac{+1}{20}$

$v=+30cm$