First, obtain an LED, turn it on, and look at it through a spectroscope. Print the chart below and use it to record the spectrum of light emitted.
Next, open the Emission version of the Gas Lamp Spectroscopy computer program and place the unknown gas tube in the gas lamp socket.
When the unknown is in the socket, you can create your own spectrum by dragging the lines near the top of the screen. Using the edit properties button, change the computer-generated spectral lines so that the spectrum is similar to the one you observed for an LED.
Got it? Now how is the spectrum in the computer program both similar and different from the spectrum of the LED through the spectroscope?