E1 practical: Helium spectrum
In this practical you are going to view the line spectrum from a low pressure helium source through a pair of spectral glasses. The spectrum glasses are actually covered in very fine slits, such an arrangement is called a “diffraction grating”. The spectrum is formed because different wavelengths of light are diffracted by different amounts according to the equation dsinϑ=nλ. where d is the separation of the slits in...