Question

what distance from the lens a 5 cm tall object be placed so that it forms an inverted image at 15 cm from the lens? Also calculate the size of the image formed. Given that, f=15cm.​

Answer 1

Explanation:

THE lens is a CONVEX lens....

Answer 2

Answer:

The object should be placed in infinity and the the image is  a point.

Explanation:

The lens is concave lens, f=-15cm

u=? v=-15cm

$h_{1}=5cm$ and $h_{2} =?$

$\frac{1}{v} -\frac{1}{u} =\frac{1}{f} \\ \frac{1}{u} =\frac{1}{v} -\frac{1}{f} =\frac{1}{-15} +\frac{1}{15} =0$

u=infinity

$m=\frac{h_{2} }{h_{1} } =\frac{v}{u} =\frac{v}{u}h_{1}\\ h_{2} =0$

The height of image is zero which means it is a point.