This chapter takes the reader one step further to perform more complex experiments, using apparatus that are generally available in many technical laboratories. A grating spectrometer is an instrument that is used to disperse light, namely to separate it to different wavelengths. The data obtained from a spectrometer is a plot of signal versus wavelengths. A spectrometer consists of a light source, a component to split the light spectrum, a detector or a detector array, and collecting optics. The diffraction grating should be rotated until the diffracted light appears on the screen, with the red color farthest from the slit and blue closest. This "spectrometer" utilizes a light source, a digital video disk to split the light spectrum, and a camera to detect the diffracted light. Halogen flashlights work best. Avoid using a white Light Emiting Diode flashlight, because the output spectrum is not as continuous in the visible spectrum as a halogen flashlight.