Question

calculate the focal length of the lens used for correcting his distant vision

Answer 1

Given that,

The lens used for correcting his distant vision power is 5.5 D.

We know that,

Power :

Power is equal to the reciprocal of focal length.

In mathematically,

$P=\dfrac{1}{f}$

Where, f = focal length

P= power

We need to calculate the focal length of the lens

Using formula of power

$P=\dfrac{100}{f}$

$f=\dfrac{100}{P}$

Put the value into the formula

$f=\dfrac{100}{5.5}$

$f=18.2\ cm$

Focal length is positive then the lens will be convex lens.

Hence, The focal length of the lens is 18.2 cm.