Series and Parallel Circuits Basics
Name:_____________________________________________
Directions:
1. Log on to your computer
2. Go to the following website:
http://phet.colorado.edu/index.php
3. Click the button that says “Play with sims…”
4. Click on the application that says Circuit Construction Kit (DC only). It should be
the first box.
5. Click “Run now.”
You now have the raw material to create a circuit. Take a moment to look over the site
and find all the different materials. To build a circuit you will need several wires, a light
bulb, a voltage source, a voltmeter, and a non – contact ammeter. Play with it to see how
to grab and manipulate these tools.
Click the reset button.
A. Series Circuits
Build a simple series circuit that consists of 6 pieces of wire, 1 light bulb, and 1 battery
(voltage source). In order to complete the circuit, the red circles at the end of each must
overlap. Please note that the light bulb also has TWO circles. Your circuit is complete
and working when the light comes on and the blue dots begin moving.
Draw a picture of your circuit here.
What do you think that the moving blue dots represent?
Use the tools at the side to get a voltmeter and a Non-contact ammeter. Put the voltmeter
near the battery and place the red tab at one end and the black at the other.
What is the voltage? __________
Place the ammeter crosshairs over the moving blue dots. What is the reading? _______
What does this tell us about the circuit?
Use the left button to play with the resistance and voltage of the battery. Make
observations on how this changes the readings on the voltmeter and ammeter. Record
your observations below. Be sure to record the changes you made and then the effects.
Click the advanced tab and alter the resistivity of the wire. Record your observations.
Raise your hand and let your teacher check off your working series circuit.
Click the reset button to begin working on a parallel circuit.
B. Parallel Circuits
Parallel circuits provide more than one path for electrons to move. Sketch below a
parallel circuit that includes 10 wires, 2 light bulbs and 1 voltage source.
Create this using the simulator tool. The blue dots will be moving and both lights will be
on once the circuit is complete. Raise your hand so that your teacher can check off your
parallel circuit.
Use the voltmeter and non-contact ammeter to measure electron flow and push.
Voltage:_______
Ammeter:______
How does this compare with your observations in the series circuit? Is this surprising?
WHY or WHY NOT?
Alter resistance and voltage and record your observations below.
Now right click on one of the wires connected to a light bulb. Remove the wire and
record your observations.
Does this affect the voltage, amperes, or visually change the appearance of the light bulb?
Replace the wire. Now remove one of the wires touching the voltage source. What
happened?
What is the difference between removing the first wire and the second? Why is this
significant?
C. Comparisons
Create a second series circuit and record your observations about the two once they are
side by side.
You may use the tool to play around. Create a circuit using a switch. Diagram your
circuit below and show your working circuit to the teacher to receive extra credit points.
Record any observations below.
D. One Light Bulb in SERIES CIRCUIT
1. Build this circuit:
What do the blue dots represent?
From which end of the batteries are they
flowing?
2. Select the “Voltmeter” tool from the right side and connect it to your circuit as
shown below.
What does the voltmeter read? (Use proper units)
Take one of the batteries away. What happens to the
light bulb? What happens to the voltmeter reading?
E. Two Light Bulbs in SERIES CIRCUIT
1. Build this circuit:
What happened to the brightness of the
bulbs?
Why do you think this happened?
2. Test your circuit with the voltmeter as shown below.
What does the voltmeter read?
Move the right prong so it is on the
wire in between the 2bulbs. What
happened to the voltmeter reading?
Why do you suppose this happened?
F. Adding a Switch in a Two Light Bulb SERIES CIRCUIT
1. Insert a “switch” between the negative end of the batteries and the first light bulb.
What happens to the two light bulbs when the switch is open? What happens to
them when the switch is closed?
2. Move the switch so that it is in between the two bulbs. What happens to the bulbs
when the switch is open? What happens to them when it is closed?
G. Two Light Bulbs in PARALLEL CIRCUIT
1. Construct this circuit:
Compare the brightness of these two bulbs to
the brightness of the two bulbs in series circuit.
Why do you think the brightness is different? It’s still 2 bulbs and 2 batteries,
right?!?!
2. Test your circuit with the voltmeter as shown below.
What does the voltmeter read?
Move the right prong so that it, again, is on
the wire in between the 2 bulbs. What does
the voltmeter read?
Explain why you think both readings are the same.
H. Adding a Switch to Two Light Bulbs in a PARALLEL CIRCUIT
1. Insert a switch in between the negative end of the batteries and the first light bulb.
What happens to the light bulbs when the switch is open? When it is closed?
2. Move the switch so that it is in between the two light bulbs. What happens to the
light bulbs when the switch is open? When it is closed?
I. Reflection Questions:
1. Draw a series circuit with two light bulbs. Using “light ray lines” indicate light
brightness of the two bulbs.
2. Draw a series circuit with two light bulbs and an OPEN switch (where ever you
want to put it). Indicate light brightness of both lights.
3. Draw a parallel circuit with two light bulbs. Indicate light brightness.
4. Draw a parallel circuit using two light bulbs and a switch (where ever you want to
put it). Indicate light brightness of both lights.
5. How does the type of circuit affect the brightness of two light bulbs?
6. When is a series circuit beneficial? Give an example of a series circuit that you
are familiar with.
7. When is a parallel circuit beneficial? Give an example of a parallel circuit that
you are familiar with.
J. Experiment!
Try changing around the position of the bulbs. Add bulbs. Add batteries. Change the
positions of the batteries in the circuits. EXPLORE!!!