Electric Circuit Lab
Remember, if at anytime you create a circuit
that I have not assigned, you will receive a zero
on the assignment.
Materials:
Voltage Generator
Ammeter
Voltmeter
2 resistors
5 banana leads
2 alligator-banana leads
1 double alligator lead
Button switch
Holiday Lights ( 2 single,1 double,1 triple,
and 1 quadruple bulbs in series)
Before beginning:
Connect a banana plug to the black plug on the Voltage Generator and the black plug on the voltmeter. Connect
a banana plug to the red plug on the Voltage Generator and the red plug on the voltmeter labeled “15V.” Turn
the voltage generator on until the voltmeter says “6V.” Do not touch the knob on the voltmeter again, but
unplug the banana plugs from the voltmeter. You will use a switch to open and close the circuit.
Light Bulb Series Circuits:
1. Connect a banana lead to the voltage generator and put the other end in the switch.
2. Connect an alligator-banana lead to the other plug in the voltage generator and put the alligator clip one
side of a single bulb.
3. Take another alligator-banana lead and complete the circuit by connecting the other side of the switch
and one to the other end of the single bulb.
4. To get the bulb to light, close the switch.
5. On your lab paper, draw the circuit diagram and label it “Circuit 1.”
6. Open the switch, remove the single bulb from the circuit and replace with the double bulb.
7. To get the bulb to light, close the switch.
8. On your lab paper, draw this new circuit diagram and label it “Circuit 2.”
9. Open the switch, remove the double bulb from the circuit and replace it with the triple bulb.
10. To get the bulb to light, close the switch.
11. On your lab paper, draw this new circuit diagram and label it “Circuit 3.”
12. Open the switch, remove the triple bulb from the circuit and replace it with the quadruple bulb.
13. To get the bulb to light, close the switch.
14. On your lab paper, draw this new circuit diagram and label it “Circuit 4.”
Questions to be answered on your lab paper:
1. Which circuit produced the brightest light, Circuit #4 or Circuit #2?
2. Which was the brightest of all the circuits? Why?
Light Bulb Parallel Circuits:
1.
2.
3.
4.
5.
6.
7.
Remove the quadruple bulb series from the circuit.
Replace with the two single bulbs in parallel.
On your lab paper, draw this circuit diagram and label it “Circuit 5.”
Close the switch and observe the brightness.
Open the switch, remove one of the bulbs.
Close the switch and observe the brightness.
Open the circuit and disassemble it.
Questions to be answered on your lab paper:
3. How does the brightness of two bulbs in parallel compare to the brightness of one bulb?
4. How does the brightness of two bulbs in parallel compare to the brightness of two bulbs in series?
5. What does this circuit tell you about parallel circuits? (Hint: think about current and voltage)
Resistors in Series:
1. Connect a banana lead to the voltage generator and plug it into the ammeter.
2. Connect a banana lead to the other plug in the ammeter and connect to the switch.
3. Connect an alligator-banana lead to the other plug in the voltage generator and attach to your smallest
resistor.
4. On your lab paper, write down the value of the resistor. Resistor #1:
Ω
5. Use an alligator-banana to complete the circuit by connecting the other side of the switch and one to the
other end of the resistor.
6. To run electricity through the circuit close the switch.
7. Important note, if the meter goes below zero, the current is just in the opposite direction, switch
the plugs in the ammeter.
8. On your lab paper, write down the value of the current read off the ammeter.
A
(Ammeter reading) Current #1:
9. Open the switch, take one double alligator lead and unclip one side of the resistor from the circuit and
insert this second resistor.
10. On your lab paper, draw this circuit and label it “Circuit #6.”
11. On your lab paper, write down the value of the resistor. Resistor #2:
Ω
12. Close the switch and read the ammeter again.
13. On your lab paper, write down the value of the current read off the ammeter.
A
(Ammeter reading) Current #2:
14. On your lab paper, add the two resistors together. Total resistance:
Ω
15. Open the switch, disassemble the circuit.
Questions to be answered on your lab paper:
6. How did Current #1 compare to Current #2?
7. Why did the current change as you added resistors in series?
8. Using a voltage of 6 V and the printed resistance on the resistor, use Ohm’s Law to calculate Current #1
from your experiment. Show GUESS.
9. Using a voltage of 6 V and the printed resistance on the second resistor plus the resistance on the first
resistor, use Ohm’s Law to calculate Current #2 from your experiment. Show GUESS.
10. Compare your answer to #8 to the Current #1 you measured off the ammeter and your answer to #9 to
the Current #2 you measured off the ammeter. If they’re off (which is normal) think of three reasons
why.
Conclusion Questions to be answered on your lab paper:
11. If you were to make a circuit with one bulb and one resistor, how would the brightness compare to your
Circuit #1?
12. Draw the circuit described above and label the value of the battery, and resistor.
13. Did the two bulb series or two bulb parallel circuit have more resistance?
14. Would you want your house outlets hooked up in parallel or series? (Hint: look at #13)
15. If you could build any circuit that you wanted to with these supplies, what would you make? Draw the
circuit as completely as possible and label it “Circuit #7.”
Make sure that your have seven circuits drawn
on your paper correctly labeled and have
answered all questions!