A beam of light with wavelength $\lambda$ is incident on a diffraction grating whose slit spacing is $d$. A sequence of lines appears on a screen. What is the angle $\alpha$ between the two first order lines?
- A$\sin^{-1}\!\left(\frac{\lambda}{2d}\right)$
- B$\sin^{-1}\!\left(\frac{\lambda}{d}\right)$
- C$2\sin^{-1}\!\left(\frac{\lambda}{2d}\right)$
- D$2\sin^{-1}\!\left(\frac{\lambda}{d}\right)$