Question

focal length of convex lens 20 cm what will be the distance of object when the image is formed at the distance of 40 cm what is the magnification​

Answer 1

Answer:

f=20cm,v=40cm,u=?,M=?.

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

$\frac{1}{20} = \frac{1}{40} - \frac{1}{u}$

$\frac{1}{20} - \frac{1}{40} = - \frac{1}{u}$

$\frac{2 - 1}{40} = - \frac{1}{u}$

u=40