Light is incident on a diffraction grating with $7900$ lines$/$cmlines$/$cm and the pattern is viewed on a screen located $2\mathrm{.}7$ mm from the grating. The incident light beam consists of two wavelengths, $1=4\mathrm{.}4107$m$1=4\mathrm{.}4107$m and $2=6\mathrm{.}4107$m$2=6\mathrm{.}4107$m$.$