Your Name Goes Here
First and Last
Date Goes Here
NOTE: Anything in italics should be erased!
Ohm's Law and Parallel Circuits
How can Ohm’s Law be applied in a parallel circuit?
Hypothesis: We are not performing a typical lab, where we are
investigating one variable with respect to another. Instead we are
building a parallel circuit, recording voltages and current in
different places, calculating resistances based on what we know
about Ohm’s law in series circuits and seeing if we can verify some
well known relationships. So Hypothesis, Variables, is a bit
“unconventional” and artificial in this case, but for the sake of
familiarizing ourselves with these parts of a lab write-up, lets
soldier on. 
Here is one possible hypothesis for an investigation of Ohm’s Law
in parallel circuits:
If we add loads in parallel to a circuit, then the voltage drop in each
branch will
______________________________________________
because________________________________________
______________________________________________
Variables: Again, we are observing and verifying instead of
testing one variable against another
- state independent and dependent variables
- state the important variables to control
- explain why the variables must be controlled
Method:
Material List
-one breadboard
-three different resistors
-three identical LEDs
-one multimeter
-battery pack with two working batteries (2.7V minimum)
-4 extra wires for connecting multi meter
Procedure
1. Record voltage from battery pack
2. Construct parallel circuit with three LEDs, each with a different
resistor in its branch.
3. Record current from battery by placing ammeter into the circuit
next to the battery (before branching off toward a bulb). Use extra
wire to place ammeter in series next to the battery.
4. Record current in each branch by placing ammeter into the
circuit IN each branch.
5. Record voltage drop across each resistor.
6. Record voltage drop across each LED.
7. Record a photograph of your circuit with labels for branch 1, 2,
and 3.
Data Collection
This is where your data table should appear. It should be on its
own page. Do NOT squeeze it under Procedure. New Page! Copy
and Paste from Excel.
Data Processing
Give one example of each calculation you performed whether it
was done by a formula entry into Excel or not. Clearly indicate
what you are giving an example of.
Conclusion
Go back to the hypothesis. Do your results indicate the hypothesis
is correct?
Now in this lab we looked at much more than just this hypothesis.
For the conclusion to this activity, please answer the following:
1. Do your results indicate that your hypothesis is correct? If not,
what do the results indicate?
2. What do you notice about the voltage drop in each branch of
your parallel circuit?
3. What do you notice about the current in each branch of your
circuit compared to the current in the circuit overall?
4. What can you say about the sum of all the resistances in each
branch and the total resistance of the circuit? (Give and example,
and indicate whether the sum is more or less or equal to the total
resistance.)
Evaluation
What mistakes did you make? What might you do differently next
time? How might mistakes have affected your outcome? What
outcomes indicate that errors were made?