Electric Parallel Circuit Lab (50 points)
Name (s):
Warning: Do not touch any live wires or leads. Show your circuit to your teacher before
connecting the battery.
Materials:
power supply, board wires, voltmeter, ammeter, switches
Procedure:
connect the resistors in parallel, measure voltage and current
determine the resistance for each resistor with Ohm’s law
always connect the voltmeter in parallel, ammeter in series
draw circuit diagrams for parallel
Calculations:
R=V/I
P=VI
Procedure: Connect the given resistors in parallel. One 250  and one 500 . Measure the voltage
across each resistor and the current in the circuit. Use the DC power supply as your power source
and carefully adjust reading to 6 V, DC. Before connecting power supply, make sure to show your
circuit to the teacher for approval. Use a switch in the circuit and close the switch only for as long as
you need to note the ammeter and voltmeter readings. Circuit correctly connected (5 points)
After finishing put everything back in place, disconnect power supply (5 points)
Draw the circuit diagrams neatly in all three cases, labeling your components fully.
Parallel Circuit Data (10 points)
Resistors
Theoretical
Resistance
()
2 parallel
250 ,
500 
Measured
Voltage
(VT)
Measured
Current in
each
branch
(A)
I1 =
Total
Current in
Circuit (IT)
(A)
I2 =
Verify: (10 points)
Is the theoretical resistance equal to the measured resistance? Verify.
Is the sum of I1 and I2 equal to the total current IT? Verify.
Measured
Resistance
RT = V/IT)
()
Power
(V x IT)
(W)
Circuit + Diagram: (10 points)
Conclusions (10 points)
1. A 40 W and 100 W bulb are connected in parallel. Which glows brighter?
2. As you add more resistances to a parallel circuit, what happens to the overall resistance and
total current in the circuit?
3. Are the lights in your home in series or parallel or a combination of both?
4. A 3-way bulb uses two filaments to generate the light. Are they connected in series or
parallel? Hint: The brightest light is always the sum of the two dimmer lights.(Example: 50W,
100W, 150W or 100W, 200W, 300W)
5. Name any three precautions you should use when dealing with power supplies or probing
unknown circuits?