Question

A person suffering from myopia can see objects placed at 15 cm clearly. What type and of what focal length of lens should he use to see objects placed 60 cm away?

Answer 1

Dear Student

$$\begin{gathered} imagedis\tan cev=-15cm \\ objectdis\tan ceu=-60cm \\ lensformula \\ \frac{1}{f}=\frac{1}{v}-\frac{1}{u} \\ \frac{1}{f}=\frac{1}{-15}-\frac{1}{-60} \\ \frac{1}{f}=\frac{-4+1}{60}=\frac{-3}{60} \\ f=-20cm \\ Lensshouldbeconcavelens \end{gathered}$$

Regards