$[-/1$ Points$]$

SERCP$1125\mathrm{.}6.$P$\mathrm{.}049.$

A diffraction grating has a third$-$order resolving power of $1,220.$

$$

$($a$)$ Find the number of illuminated lines on the grating.

$$

$($b$)$ Calculate the smallest difference $($in nm $)$ in wavelengths surrounding $540$ nm that can be resolved in the first$-$order diffraction pattern.

$$ nm

Need Help? $$