Light with wavelength $\lambda$ strikes a diffraction grating at normal incidence, as illustrated. The angle between the two second-order maxima is $\varphi$. Which expression determines the spacing between the lines on the diffraction grating?
- A$\dfrac{\lambda}{\sin \varphi}$
- B$\dfrac{\lambda}{\sin (\varphi / 2)}$
- C$\dfrac{2\lambda}{\sin \varphi}$
- D$\dfrac{2\lambda}{\sin (\varphi / 2)}$