Introduction:

The purpose of this experiment is to investigate the spectrum of light emitted by various substances using a transmission diffraction grating. Light from the emitting object is collimated in a parallel beam and then observed through the grating.

A series of colored bands of light is observed, indicating that the glow coming from the light source is not a continuous distribution of wavelengths, but rather a discrete spectrum of colors. It is the interference effect that disperses light of differing wavelengths through different angles. In addition, if one increases the observation angle far enough, one can see that the pattern repeats. This repetition is called the 2nd order spectra. In general, the location of the Nth order maximum occurs at the angle $\theta$ such that = N d, N = 1,2,3,.... where d is the separation between slits in the grating. Thus the wavelength of radiation observed at a measured angle $\theta$ can be determined.

Various emitting sources are available. Determine the nature of 3 different spectra, and compare your results with the accepted values.