A person has been using spectacles of power - 1 . 0 diopter for...

Given, $P = 2D = 2{m}^{- 1}$

Focal length is $\dfrac{1}{f} = \dfrac{2}{100}{cm}^{- 1}$

Using lens equation $\dfrac{1}{v} - \dfrac{1}{u} = \dfrac{1}{f}$

As we know, $u = - 25cm$

Then, $\dfrac{1}{v} - \left(- \dfrac{1}{25}\right) = \dfrac{2}{100}$

$⇒ \dfrac{1}{v} = \dfrac{1}{50} - \dfrac{1}{25}$

$⇒ v = - 50cm$