The spectrum of a carbon arc lamp, projected onto a screen, contains both visible and ultraviolet radiation. A wavelength shifter bar is a plastic material containing a fluorescent chemical, fluorescien. Insert the wave length shifter bar into the spectrum with light coming out the curved end aimed at the class for easier observation. For wavelengths greater than green, the spectral color is observed (red, orange, yellow). For shorter wavelengths, the chemical in the bar absorbs the incident light but re-emits that energy as green light, the characteristic color of the chemical in the plastic tube.
Use the wave length shifter bar to demonstrate the existence of ultraviolet radiation in the spectrum of the carbon arc lamp.