The SI unit of power is ___________.

The SI unit of power is dioptre.

Explanation

The power of a lens is defined as, the ability of a lens to bend the light falling on it.

Mathematically it is given as:-

$Power(dioptre)=\frac{1}{focal\ length\ (in\ meters)}$

The S.I unit of power of lens is ${m}^{-1}$, also known as dioptre (D).