# Lab 10 - Physics 101

Topics: Light-emitting diode, Evaporation, Lighting Pages: 3 (764 words) Published: August 25, 2013
Lindsay Bingham
PHY101 – 18801
8/19/2013
Electrical Components and Circuits
Purpose: The objective of this experiment was to analyze light and its relationship between energy and color of the light producing that energy. We also were in charge of measuring the rate at which evaporation occurs for rubbing alcohol depending on the different colored diodes. Materials:

* LEDs and circuits (from previous lab)
* Pipette (or eyedropper)
* Rubbing alcohol
* Index card
* 9-volt battery
* Flashlight
* Stopwatch
* Small cardboard shoe box
Procedure:
1. Set up an Excel spreadsheet listing variables: evaporation time vs. frequency of LED. 2. Make a three-sided enclosure from the cardboard box. This creates a location for applying light from the LED to the drop of alcohol while minimizing the effect of air currents on the evaporation rate. 3. Use the eyedropper to place a single drop of isopropyl alcohol on an index card within the enclosure. Try to use the same size drop each time this step is repeated. 4. Measure the time it takes for the drop to evaporate (without the LED present). The dark spot on the card caused by the alcohol will no longer be visible. You may want to use a flashlight to help with this observation. Record the evaporation time in your Excel spreadsheet. 5. Repeat the same procedure holding different colored LEDs over the alcohol drop. The current through each LED should be the same, and the distance from the LED to the drop should also remain the same for each run. 6. Repeat this procedure for each color of LED at least 10 times and calculate an average time of evaporation for each color. 7. Plot a graph of evaporation time versus frequency of the LED. 8. Look up the frequency of the diode.

9. Discuss your results and make conclusions based on these results. Data:

LED Color| Average Evaporation Rate (minutes)| Frequency of LED (Hz)| Green| 4.5| 5.77*10^14|
Blue| 4|...