Download Building Circuits (PHET) - Limestone District School Board

Circuit Lab
Parallel and Series Circuits
http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
Download the applet (click on RUN NOW). You must have Java 6 on your computer
(Mac’s won’t do this, because they won’t run Java). If you do not have the correct
version of Java on your computer, you can download it for free from
http://www.java.com/en/download/index.jsp
Wires – you can change the length and orientation of the wires by clicking and
dragging on the yellow circles on the ends of them. The little circles that are in the
wire are the electrons. They will not move until you have a complete loop from one
side of the battery to the other. Notice the speed that the electrons move, faster =
higher current.
Resistors – you can change the resistance of the resistors by right clicking on them
and opening the dialogue box. Notice that when you change the resistance, the
color bands on the resistor change colors to correspond to the resistance shown.
You can show the value on the picture by right clicking and selecting “show value.”
The default is 10 ohms, so you’ll have to change it to the correct value.
Battery – You can change the voltage of the battery by right clicking on it and
selecting “Change Voltage”. You can also show the voltage the by selecting, “show
value”. Don’t worry about changing the internal resistance of the battery. Leave it at
zero ohms. The default voltage is 9 V
Voltmeter – To use the voltmeter to find the voltage drop, you need to click on the
“voltmeter” box on the right. It will place a voltmeter on the board. You then need
to drag the voltmeter to the position that you want to use it. You can drag the red
and black leads so that they touch either side of the part of the resistor you want to
measure. Make sure that the voltage reading is positive. If it is negative, you hooked
them up backwards and need to switch them.
Ammeter – To use the ammeter, again, check the box next to “Ammeter”. This time,
the ammeter was added to the list of devices that you can place into your circuit.
Ammeters measure current and have to become PART of the circuit, so you need to
disconnect the circuit in order to place the ammeter in it. To disconnect, you need to
right click on the yellow circle on the end of the wire and select “split junction”. That
will separate the wires. Drag the ammeter from the box to place it IN the circuit and
connect it with wires to the rest of the circuit. The current will show up in the
display.
EXPLORING VOLTAGE in a SERIES CIRCUIT
Wait for the simulation window to pop up. It should look like the window shown below:
Using your mouse, you can place any circuit element into the main window by clicking, holding down the
mouse and dragging the element. Release the mouse once the circuit element is in the main window.
1. Place a battery and a bulb in the main simulation window, without connecting them. Select the
button for the voltmeter. Once you select it, a voltmeter will show up in the main window. Place the
black terminal of the voltmeter on the right contact point of the battery and the red one on the left
contact point of the battery. Measure the voltage of the battery and write it below.
2. What does voltage mean for you?
3. What do you think, does the bulb have voltage? Predict and then measure it the same way as you
measured the voltage across the battery: place the black and red terminals of the voltmeter on the
two contact points of the bulb. What was the measured voltage for the bulb?
4. After measuring the voltage of the bulb, would you like to change your definition of voltage?
Now, connect the light bulb and the battery using the wires available on the
right side of the simulation window. To break a contact made in the circuit,
right click on the contact and select “split junction”. Make sure you also
include a switch that is initially open. Your circuit should look similar to the
one shown.
5. Is there any current flowing through the circuit when the switch is open?
6. With the switch open, measure the voltage of the battery and of the resistor and record it below.
Pick the following pairs of two points in your circuit and measure the voltage between those points.
Record the measured values in the table below. For each of the lettered sections use the nearest
junction as your measure point.
Across the battery (between
the + and – terminals)
Between – and A (junction)
Between A and B
Across the bulb (between B
and C)
Between C and D
Between D and +
7. Close the switch. Place the black terminal of the voltmeter on the right side of the battery (the
negative end of the battery) and the red one on the left side of the battery (the positive end of the
battery). Pick the following pairs of two points in your circuit as in question 6 and measure the
voltage between those points. Record the measured values in the table below.
Across the battery (between
the + and – terminals)
Between – and A
Between A and B
Across the resistor (between
B and C)
Between C and D
Between D and +
8. Have any of the voltages read changed from the previously read values? Why or why not?
9. Plot the voltage across the various points in your circuit on the graph provided below:
9
6
3
0
+
- A B C D
Points in the circuit
+
10. Is your definition of voltage still valid? Would you like to change it?
Build a series circuit with 2 light bulbs (should look like the one below):
11. Close the switch. Place the black terminal of the voltmeter on the right side of the battery (the
negative end of the battery) and the red one on the left side of the battery (the positive end of the
battery). Measure the voltage of the battery and of the bulb and record it below. Pick the following
pairs of two points in your circuit as in question 6 and measure the voltage between those points.
Record the measured values in the table below.
Across the battery (between
the + and – terminals)
Between – and A
Between A and B
Across the bulb (between B
and C)
Between C and D
Across the second bulb
(between D and E)
Between E and F
Between F and +
12. Have any of the voltages read changed from the values read for the circuit with one single bulb?
Why or why not?
13. Plot the voltage across the various points in your circuit on the graph provided below:
9
6
3
0 + - A B C D E F +
Points in the circuit
14. Why do you think the voltage across one of the light bulbs in the 2 light bulb circuit (circuit 2) is
different than the voltage across the light bulb in the one light bulb circuit (circuit 1)?
15. Can you find a relationship between the voltage between different points in a series circuit and the
voltage of the battery? In other words, how are the battery voltage and the light bulb voltage
connected?
16. If in circuit 2 you are to use two resistors with different resistance, would the voltage across them
still be the same? If not, which one do you think would have a greater voltage? Explain your answer.