If $\hat{\mathrm{i}}$ denotes a unit vector along an incident ray, $\hat{\mathrm{r}}$ a unit vector along the refracted ray into a medium of refractive index '$\mathrm{\mu }$ ' and $\hat{\mathrm{n}}$ a unit vector normal to the boundary of the media directed towards the incident medium, then the law of refraction can be written as

• A

  $\hat{\mathrm{i}}.\hat{\mathrm{n}}=\mathrm{\mu }\left(\hat{\mathrm{r}}.\hat{\mathrm{n}}\right)$

• B

  $\hat{\mathrm{i}} \mathrm{x} \hat{\mathrm{n}}=\mathrm{\mu }\left(\hat{\mathrm{n}} \mathrm{x} \hat{\mathrm{r}}\right)$

• C

  $\hat{\mathrm{i}} \mathrm{x} \hat{\mathrm{n}}=\mathrm{\mu }\left( \hat{\mathrm{r}} x \hat{\mathrm{n}}\right)$

• D

  $\mathrm{\mu }\left(\hat{\mathrm{i}} x \hat{\mathrm{n}}\right)=\hat{\mathrm{r}} \mathrm{x} \hat{\mathrm{n}}$