Question

One end of a cylindrical glass rod ends in a hemispherical surface of radius R = 20 mm.
- Find the image distance of a point object on the axis of the rod, 80 mm to the left of the vertex. The rod is in air.

• A. 120 mm
• B. -120 mm
• C. -80 mm
• D. 60 mm

Answer 1

The correct option is A

120 mm

${\mu }_1=1,{\mu }_2=1.5,R=+20mm,u=-80mm$
$\frac{1.5}{v}-\frac{1}{-80}=\frac{1.5-1}{20}$
$v^{\prime }=+120mm$
The image is therefore formed at the right of the vertex (v is positive) and at distance of 120 mm from it.