Question

A compound microscope has a magnification of $30$. The focal length of the eye-piece is $5$ cm. If the final image is formed at the least distance of distinct vision $25cm$, the magnification produced by the objective is

• A. $5$
• B. $7.5$
• C. $10$
• D. $15$

Answer 1

The correct option is A $5$

$M=30$

$f_e=5cm$

$v_e=25cm$

$M_0=?=\frac{v_0}{u_0}$

$M=30=M_0(1+\frac{25}{5})$

$30=M_0\times 6$

$M_0=5$