Using Ohm’s Law and Building a Circuit
Lab #10
Name:
Aile Pham
Class:
14989
Date:
8/7/15
Purpose:
The purpose of this lab is to demonstrate understanding of the relationship between light energy and the color of the light producing that energy, and being able to calculate the proper current for each color LED used.
Procedures:
Apparatus:
There is no apparatus used for this lab.

Required Materials:
The required materials for this lab includes light emitting diodes (red, green, blue), wire, alligator clips, resistors pipette, flashlight, rubbing alcohol, stopwatch, small cardboard box and a 9 volt battery.
The 9 volt battery used for this lab is from the brand Rayovac and the isopropyl alcohol used was 91%.

1. Assemble the DC series circuit, by connecting the LEDs, resistor, and battery together.
2. Create 3-sided enclosure card board box.
3. Place a drop of isopropyl alcohol on an index card and record how long it takes for it to evaporate. You can tell when it is fully evaporated when the dark spot, caused by the alcohol, is not visible.
4. Repeat this step, but with each LED color above the alcohol drop. Attempt to keep all variables constant, such as distant from the alcohol.
5. Perform each trial, for each color, at least ten times and record the results on an Excel spreadsheet.
6. Plot a graph of evaporation vs. frequency of the LED.
Data:
Lab Set Up:

Figure 1 shows how the lab was set up, and most of the required materials. The resistor used for this lab was the one with the brown, black, red and gold bands. The circuit was already built in this photo.
The Experiment:

Image 1 shows the first part of the experiment where it was recorded on how long it would take the rubbing alcohol to evaporate without the LEDs.

Trial
How long it took the rubbing alcohol to evaporate (seconds)
1
117
2
89
3
137
Table 1 shows the results how long it took the isopropyl alcohol to evaporate without the circuit. The average for this is 114.3 seconds.

Image 2 shows the second experiment where it was recorded how long it took the rubbing alcohol to evaporate with the LED present. In this picture, the blue LED was used. It was quite hard to take pictures of this process.

Trial
Time it took the rubbing alcohol to evaporate with the blue LED
1
166
2
171
3
167
4
160
5
174
6
166
7
158
8
162
9
155
10
170
Table 2 shows the results how long it took the isopropyl alcohol to evaporate with the blue LED. The average for this is 164.9 seconds.

Trial
Time it took the rubbing alcohol to evaporate with the red LED
1
201
2
199
3
197
4
197
5
204
6
202
7
196
8
199
9
197
10
198
Table 3 shows the results how long it took the isopropyl alcohol to evaporate with the red LED. The average for this is 199 seconds.

Trial
Time it took the rubbing alcohol to evaporate with the green LED
1
183
2
180
3
185
4
187
5
191
6
175
7
196
8
180
9
184
10
181
Table 4 shows the results how long it took the isopropyl alcohol to evaporate with the green LED. The average for this is 184.2 seconds.

LED color
Frequency (Hertz)
Blue

Red

Green

Table 5 shows the frequency of each color that was used in this experiment.
Source: http://classroom.synonym.com/frequency-led-lights-9592.html
Evaluation of Data:
Calculations:
Calculations for the resistor used:
There were no calculations used in this lab.

Graphs:

Figure 3 shows the relationship between frequency and the average time of evaporation of the isopropyl alcohol, with the LED.
Results:
The standard variable, the evaporation rate of the rubbing alcohol without the LED present, was 114 seconds. The standard evaporated fasted than the rates of evaporation with the LED.
The blue LED has the highest frequency and had the quickest evaporation