A simple microscope is rated 5 X for a normal relaxed eye. What Nvill be its magnifying power for a relaxed farsighted eye whose near point is 40 cm?

Explanation

The simple micrscope has magnification of 5 for normal relaxed eye `(D=25cm)` Because the eyeis relaxed the image is formed at infinity (normal adnustement).
so, `m=5 D/f=25/f`
`rarr f=5cm ` For the relaxced far sighte eye D=40 cm
so, `m=D/f=40/5=8`
so its magnifying power is 8.