Understanding Series Circuits
Name ______________________________
Date ____________________________
You are designing a Holiday light and Santa display at your house. You need to decide what you may
want to place in series and what you may want to place in parallel (next activity). First you must
discover how each type of circuit behaves. You will do this by following a series of labs using a
computer simulation.
Goals:
•
•
•
Correctly place voltmeters and ammeters in a series circuit.
Find the voltage and amperage in series circuits.
Determine which is constant in a series circuit, voltage or amperage.
1. Open the website, http://phet.colorado.edu/ and search for “Circuit Construction Kit”.
2. Under Simulations, click on “Circuit Construction Kit (DC Only)”
3. Make a series circuit using three resistors and one battery (similar to the one in the picture
below). Remember that a series circuit has only one path for electric current to flow.
4. Turn on Show Values so you see the resistor values.
5. Change the resistor values by right clicking on each resistor. Make the resistors at least 10 Ohms
different from one another (Ex. 10Ω, 20 Ω and 30 Ω OR 15Ω, 25 Ω and 35 Ω, etc…). Make sure
to check Show Values after you are done.
6. Record the resistor values on the data table on the next page.
7. Let’s measure the current (flow) through each resistor and the battery. Here is how:
a. Under Tools, check Non-Contact Ammeter and move it after each resistor and then after
the battery, as shown in the picture below.
b. Record the amount of Amps measured by the Non-Contact Ammeter on the data table on
the next page.
8. Now you are ready to measure the voltage (pressure) across each resistor and the battery. Here
is how:
a. Under Tools, check Voltmeter and place the leads across each resistor and across the
battery, as shown in the picture below.
b. Record the amount of Volts measured by the Voltmeter on the data table on the next
page.
Data Table
Resistor size (R) in
Ohms (Ω)
Voltage (V) in
Volts (V)
Current (I)
In amps (A)
***Calculated
Resistance (R) in
Ohms (Ω)***
Resistor 1
Resistor 2
Resistor 3
***Battery
*** Use Ohm’s Law (V=IR) to calculate the resistance of the battery***
Questions
1. Unhook one of the resistors from the circuit. What happens to the circuit? Why does this
happen? ______________________________________________________________________
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______________________________________________________________________________
2. How would this affect your holiday display? _________________________________________
______________________________________________________________________________
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3. In your holiday display would you use series connection? Why? __________________________
______________________________________________________________________________
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Numerical Analysis
4. Look at the values for Voltage (column 2). What did you find out about the voltage across the
resistors and the voltage across the battery? Is there any type of mathematical relationship
between these numbers? If so, explain what this relationship is.
5. Look at the values for Current (column 3). What did you find out about the current flowing
trough the resistors and the current through the battery? Is there any type of mathematical
relationship between these numbers? If so, explain what this relationship is.
6. Look back at your answers to questions #4 and #5. Which of the following best describes a series
circuit? Circle ALL that apply:
a) Vbattery = V1 + V2 + V3
d) Vbattery = V1 = V2 = V3
b) Ibattery = I1 + I2 + I3
e) Ibattery = It = I1 = I2 = I3
c) Rbattery = R1 + R2 + R3
f) Rbattery = R1 = R2 = R3