A simple microscope is rated `5 X` for a normal relaxed eye. What will be its magnifying power for a relaxed far sighted eye whose near point is `40 cm`.

Answer

8

Explanation

For normal eye, `d = 25 cm, m = 5`
As `m= (d)/(f), f = (d)/(m) = (25)/(5) = 5 cm`
For relaxed far sighted eye, `d' = 40 cm`,
`f = 5 cm` :. m' = (d')/(f) = (40)/(5) = 8`.