Question

An object is placed at 30 cm in front of the convex lens of focal length 10 cm. The distance of the image from the lens is + ___ cm.

Answer 1

From Len's formula, $\frac{1}{v}$ - $\frac{1}{u}$ = $\frac{1}{f}$

f = + 10 cm (convex lens)

u = - 30 cm

$\frac{1}{v}$ + $\frac{1}{30}$ = $\frac{1}{10}$

$\frac{1}{v}$ = $\frac{1}{10}$ - $\frac{1}{30}$ = + $\frac{2}{30}$

v = + 15 cm