Lab # 9
Use Ohms Law to calculate the proper resistance needed to produce a specific current compatible with the voltage of battery used.
Use the proper electrical units with the proper electrical quantities.
Use the multimeter to measure voltage and resistance in an electrical circuit.
9 Volt Battery
Light emitting Diodes (Red, Green, Blue)
1. With the components provided in the lab kit, “build” the DC series circuit.
2. Using the resistors provided, that limits the current to less than 20 ma, use the multimeter to measure the voltage drops across each component in the circuit.
3. When using the multimeter to measure, start with the highest scale and work down to the scale that provides the most readable voltage value. Record the data found in an Excel spreadsheet.
4. Use the voltage drops across the resistor and the value of the resistor to calculate the current flow through the resistor. ( the same current flows through the LED.)
5. With Excel and the values found for the voltage across the LED and current through the LED, plot a graph to determine if the LED obeys Ohm’s Law.
Results and evaluation of data:
The plot of the current vs. voltage does not show a straight linear line. However, I do believe this is related to difficulties in using the multimeter (i.e. user error)not that the LED did not obey ohm's law.
Conclusions: The purpose of this experiment was to assemble a simple series circuit consisting of a power source (9v Battery), a resistor (limits the flow of electric current), and LED's (convert electrical energy to light). A multimeter was used to measure voltage drops across the various components.
As indicated earlier, the data obtained