$A$ person cannot see objects clearly beyond $2.0 \, m$. The power of the lens required to correct his vision will be:

$A$ person wears glasses of power $-2.0 \, D$. The defect of the eye and the far point of the person without the glasses will be

$A$ person can see clearly only up to a distance of $25 \, cm$. He wants to read a book placed at a distance of $50 \, cm$. What kind of lens does he require for his spectacles and what must be its power?

The near point of a person is $75 \, cm$. In order for him to be able to read a book at a distance of $30 \, cm$,what should be the power of the spectacle lenses?

$A$ person wears normal spectacles in which the distance between the glasses and the eyes is approximately $2 \, cm$. The power required is $-5 \, D$. If he wears contact lenses,then the required power is ......... $D$.

$A$ person uses a lens of power $+3 \text{ D}$ to normalize vision. The near point of the hypermetropic eye is ....... $m$.