Question

A divergent lens has a focal length of 30cm. At what distance should an object of Height 5cm from the optical centre of the lens be placed so that it's Image is formed 15cm away from the lens ? Find the size of Image also

Answer 1

10cm from away from centre . Image size will be 1.5 cm

Answer 2

F = -30 cm

Height of object = 5 cm

V = 15 cm

$\bf\huge\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$

$\bf\huge\frac{1}{-30}=\frac{1}{15} - \frac{1}{u}$

$\bf\huge\frac{1}{u} = \frac{1}{15} + \frac{1}{30}$

$\frac{1}{u} = \frac{2+1}{30}$

= $\bf\huge\frac{3}{30}$

=> U = 10 cm

Magnification = $\bf\huge\frac{-V}{U}$

$\bf\huge\frac{-15}{10} = \frac{hi}{5}$

hi = -7.5

$\bf\huge\boxed{\boxed{\:Image\:=\:Virtual,\:Enlarged,\:Erect}}}$