Emission Spectroscopy
Print off these 2 pages for the data table and lab writeup.
1. Pick up a diffraction grating from the front lab table.
2. Holding the diffraction grating up at your eye, look up at one of the fluorescent lights in the ceiling (white light). Draw what you see on the data table you printed off in the section labeled WHITE LIGHT. Since red light has the lowest frequency, always draw the red to the LEFT - as compared to violet light which has the highest frequency, always draw violet towards the RIGHT. Use the colored pencils. As you draw your bands of color, remember that white light emits a CONTINUOUS SPECTRUM so your colors should "blend" together as you draw from red to violet light.
3. At the front of the room, there will be different cathode ray tubes (CRTs) with 5 different elements.
4. Using the diffraction grating, draw the patterns of the bands of colored light you see onto your data sheet. Again, draw lowest frequencies of light to the left, higher frequencies to the right. On the 5 different samples, you will NOT see a continuous spectrum - you see an EMISSION SPECTRUM and so you should be drawing DISTINCT color stripes - NOT blended together! These will look TOTALLY different from the white light! You will be graded both on the accuracy in the placement of the lines relative to each other and their colors. NEATNESS counts!
Remember the order of the colors of the rainbow:
ROY
G BIV
- red, orange, yellow,
green, blue, indigo,
violet.
QUESTION #1: Your white light drawing should look very different from the emission spectra for the 5 pure elements. How is your white light drawing different from your drawings of the other elements? Why is the white light so different?
QUESTION #2: Compare your bands of light (when you used the diffraction gratings) to the bands of light on this website: http://www.colorado.edu/physics/2000/quantumzone/ Read carefully the first part of this website. Scroll down to the part where you can select different elements. Use this information to compare what YOU saw to what you SHOULD have seen. Be specific.