9-15-04
Identification of Wavelengths: Part 1
The purpose of this lab is to measure and identify the specific wavelengths of light emitted by a mercury pen-light lamp. We will shine a mercury pen lamp into a spectrometer, which will output the wavelength spectrum of the light from the lamp.
When the electrons in an atom become excited, perhaps by being struck by an incoming electron, they bounce up to a higher energy level as they absorb the energy of the incident particle. They are less stable as a result of being at a higher energy level, however, and so they fall back down to their normal state and release the excess energy in the form of light. Because the changes in energy levels correspond to distinct energy values, each element emits its own particular set of light frequencies – a wavelength spectrum. Our goal is to measure the wavelength spectrum of mercury gas.
For our experiment, we will use a spectrometer which is attached to a printer. The spectrometer has a ‘slit housing,’ which allows light to enter. We will place the mercury lamp as close to this slit housing as we can, so that the mercury light will enter into the spectrometer. The spectrometer will then scan through the spectrum of light coming from the mercury lamp, looking for wavelengths between 300nm and 600nm. When the spectrometer is looking for a specific frequency, if it sees that frequency, it will generate a spike on the printer to which it is connected, the size of which corresponds to the intensity of light at that particular frequency.
We will set up the pen light as close to the spectrometer as possible, using the following settings:
- Gain Control :
- Slit Height :
- Slit Width :
- Recorder Sensitivity:
We identified the following wavelengths: