Question

A person is suffering from myopia, his far distance is 5 m. what is the focal length of his

eye lens​

Answer 1

Answer:

The focal length of his eye lens is -5m

Explanation:

The lens which is required to treat myopia is concave lens.

When the object is at Infinity the virtual image should form at 5 m.

u = ∞                                        [where u = object;

v = - 5 m                                  v = virtual image

$\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$                                 f = focal length]

$\frac{1}{f} = \frac{1}{-5} - \frac{1}{ infinity} }$

∴ f = - 5m.

The focal length of his concave lens is -5m.