A diffraction grating has \(N\) lines per unit length. Light of wavelength \(\lambda\) is incident normally on the grating. What is the condition for the \(n\)th order maximum? (\(d\) is the slit separation)

• A

  \(d \sin \theta = n\lambda\)

• B

  \(n \sin \theta = d\lambda\)

• C

  \(d \cos \theta = n\lambda\)

• D

  \(\sin \theta / d = n\lambda\)