Download Ohm`s Law, Parallel and Series Circuits Name

Ohm’s Law, Parallel and Series Circuits
Physics—Anderson
Name______________
Period ___________
In this lab you will need to circle the correct answer, you will also need to fill in answers when
needed.
Go to the following website http://www.article19.com/shockwave/oz.htm
Make a series circuit using a 10 V battery and four light bulbs, well don’t just sit there, do it now.
Switches can be turned on and off with a Ctrl right click of the mouse. You will need a wire too. If
you do it right the bulbs will go on.
Click on the visualize button at the bottom, does the current run from positive to negative or negative
to positive?
Click on the visualize button to stop it and measure the voltage, use the voltmeter at the bottom
across these. You do this by putting one lead on either side of the device being measured
Battery ____ V light bulb ______ V
Are the voltages across each light bulb the same? Yes/No
Use the ammeter to measure the current in two different places.
Current place one _____ A
current place two _____ A
Is the current the same everywhere? Yes/No
If one lights goes out do they all go out? Yes/No
Now make a series circuit with just two bulbs.
Will there be less resistance than before? Yes/No
Will the current now go up or down? _____
Measure the current in two places.
Current place one _____ A
current place two _____ A
If there are only two bulbs, make a guess as to the voltages across each one. ________ V
Measure the voltage across each bulb.
Bulb one _______ V
Bulb two _________ V
Is the sum of the voltages across each bulb equal (about) to the voltage across the battery? Yes/No
Set up a series circuit with one bulb, measure the voltage and the current.
Voltage across the bulb ______ V Current ______ A
Use ohm’s law and calculate the resistance of the bulb. ______ ohms
Use the clear button at the left corner of the page.
Make a series circuit with a battery and FOUR different types of resistors. Do it now! DON’T USE
BULBS!
Click on the visualize button. Is current flowing? Yes/No
Measure the voltage across each of the resistors. Then rank the resistors by which you believe is the 1
highest, 2 high, 3 low, 4 lowest resistance.
1 _________ V _________rank ____ ohms
2 _________ V _________rank ____ ohms
3 _________ V _________rank ____ ohms
4 _________ V _________rank ____ ohms
Now click on popups at the bottom of the page and move the hand over the resistors to determine
their resistance, complete the table above. Did the resistances match your rankings Yes/No
You need a greater voltage (push) across higher/lower resistance to keep the current the same in a
series/parallel circuit.
Make a series circuit with one ten ohm and one twenty ohm resistor, for a powers source use a
10 V battery.
What is the total resistance of the circuit ________ ohms
Calculate the current using ohm’s law. _______ A
Measure the current with the ammeter _______ A
Did it match your calculations? Yes/No
Hit the clear button and click off the popup button and make a parallel circuit using Four bulbs and
a battery. You will need some wires and the lights will go on when you complete the circuit.
If one light goes is pulled out of the circuit will the others stay lit? Yes/No
Measure the voltage across each of the bulbs and the battery
Battery ______ V out _______ A in _______ A
Bulb 1 ______ V _______ A
Bulb 2 ______ V _______ A
Bulb 3 ______ V _______ A
Bulb 4 ______ V _______ A
Is the voltage the same across all resistors in the circuit? Yes/No
Click on the visualize button. Now measure the current coming in and out of the battery and through
each of the bulbs and record in the table above.
Does the sum of current going through each branch (bulb) add up to the total current coming in and
out of the battery. Yes/No
Take a bulb out of this circuit. The total resistance go up/down. This is because there are fewer
branches (paths) for the current. T/F
Should the current coming out of the battery be higher now. Yes/No
Measure the current _______ A This is higher or lower than before.
So adding more resistors in parallel raises/lowers the total resistance, and thus raises/lowers the
current coming in and out of the battery.
Hit the clear and connect a battery and two (TEN ohm) resistors in parallel. Hit the visualize button
to see if the current will flow.
Calculate the equivalent resistance of these two resistors ____ohms
Calculate the current coming out of the battery and the current going through each of the resistors.
Calculated Battery ______ A Measured ______ A
1) Calculated ten ohm resistor ______ A Measured ______ A
2) Calculated ten ohm resistor ______ A Measured ______ A
Measure the current through the battery and the resistors and record above. Did it match your
predictions? Yes/No
What is the formula for calculating equivalent resistance?
What is a likely mistake to make when using this formula?
If there are four identical resistors that are wired in parallel the overall resistance should be reduced
by a factor of ________. Compared to a single resistor.
The current should increase by a factor of _______. Compared to a single resistor.
If four identical bulbs are connected in series the overall resistance should increase by a factor of
_______. Compared to a single bulb.
The current should decrease by a factor of ______. Compared to a single bulb.
What was the current coming out of the battery with your four bulbs in parallel? _______ A
What was the current coming out of the battery with just one bulb in series? _________ A
What was the current coming out of the battery with your four bulbs in series? _______ A
Does this match you predictions? Yes/No