1. Describe what is meant by a *diffraction grating*.
2. When monochromatic light of wavelength 590 nm illuminates a diffraction grating, a diffraction pattern is observed on a screen some distance away. The light source is replaced by one with a wavelength 450 nm. Suggest two ways in which the observed diffraction pattern on the screen would differ from the original pattern.
3. Light from a laser of wavelength 630 nm produces an interference pattern when incident on a diffraction grating labelled 600 lines mm−1 . Calculate the separation of the central maximum from the first-order maximum on a screen 5 m away.
4. Monochromatic light is incident normally on a diffraction grating labelled 600 lines mm−1 , producing an interference pattern on a screen that is 8 m away. If the distance between the second-order maximum and the central maximum is 9.5 m, calculate the wavelength of the light.