কোনটি স্নেলের সূত্র?

$\dfrac{\sin i}{\operatorname{sir} r}=\dfrac{\mu_{a}}{\mu_{b}}$

$\dfrac{\sin i}{\sin r}=\dfrac{\mu_{b}}{\mu_{a}}$

$\dfrac{\sin i}{\sin r}=\sqrt{\dfrac{\mu_{b}}{\mu_{a}}}$

$\dfrac{\sin i}{\sin r}=\sqrt{\dfrac{\mu_{a}}{\mu_{b}}}$