Alternate Pathways
Experiment – Two ways to connect light globes
Equipment
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Transformer or other power supply (set to 6 volts)
three identical light globes in stands
8 connecting leads.
ammeter
voltmeter
Method:
1. Set up the circuits shown in the diagram below.
2. Use the ammeter to measure the electric current flowing out of the power supply and into each
of the light globes in each circuit.
3. Use the voltmeter to measure the voltage drop across the power supply and each of the light
globes in each circuit
4. . Record your measurements in the table below.
Circuit 1
Circuit 2
Check:
Is the ammeter
connected properly?
How do you connect a voltmeter?
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Results:
Component
Circuit 1
Circuit 2
Current (mA)
Component
Globe X
Globe X
Globe Y
Globe Y
Power Supply
Power Supply
Globe X
Globe X
Globe Y and Z
Globe Y
Power Supply
Globe Z
Voltage (V))
Globe Y and Z
Take photos, using the webcam or other device capable of taking a digital
photograph, to show the two circuits when turned on.
Insert and label the photos as Circuit 1 and Circuit 2 and insert them here.
Answer these questions in full sentences. Type your answers in the text boxes.
1. What is the sum of the currents flowing through globes X and Y in circuit 1?
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2. What happens to the electric current flowing from the power supply when it meets a 'fork' in the
pathway?
3. In circuit 2, how does the voltage drop across globes Y and Z compare with the voltage drop
across globe X? Explain why this is the case.
In Circuit 1 the two light globes are on separate pathways – this is called a parallel circuit.
In Circuit 2 the two light globes Y and Z are on the same pathway – this is called a series circuit.
Make a general statement about electric current flowing through light globes connected in parallel.
4. Make a general statement about voltage drops across light globes connected in
parallel.
5. Re-label the diagrams of circuit 1 and circuit 2 above to highlight the components in series and
the components in parallel. Write captions for the diagrams to clearly state the difference in
brightness of the light globes in each circuit.
When you have completed this activity, email the completed MS Word document to your
teacher. Its file name must be your first initial then your last name and date in the following
format:
jsmith090809
© Commonwealth of Australia 2009
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