Question

A machinist with normal vision has a near point at 25 cm. This machinist wears +4.25-diopter eyeglasses in order to do very close work. With these eyeglasses, what is the near point of the machinist? Assume that he wears the glasses extremely close to his eyes.

Answer 1

Answer:

$d_i = 400.2 cm$

Explanation:

As we know that normal near point is given as

$d_o = 25 cm$

now the power of the lens used is

$P = 4.25 dioptre$

focal length of the lens will be

$F = \frac{1}{P} = \frac{1}{4.25}$

$F = 23.53 cm$

now we have

$\frac{1}{d_i} + \frac{1}{d_o} = \frac{1}{F}$

now plug in all values in it

$\frac{1}{d_i} +\frac{1}{25} = \frac{1}{23.53}$

$d_i = 400.2 cm$