The Distance Between the Ruled Lines on a Diffraction Grating $1900 \mathrm {~nm}$

Multiple Choice

The distance between the ruled lines on a diffraction grating is $1900 \mathrm {~nm}$ . The grating is illuminated at normal incidence with a parallel beam of white light in the $400 \mathrm {~nm}$ to $700 \mathrm {~nm}$ wavelength band. What is the angular width of the gap between the first order spectrum and the second order spectrum?

A) $6.3 ^ { \circ }$
B) $4.3 ^ { \circ }$
C) $5.3 ^ { \circ }$
D) $2.3 ^ { \circ }$
E) $3.3 ^ { \circ }$