Download lesson 2: worksheet - Walden University ePortfolio for Mike Dillon

NAME: __________________________________________ DATE: __________________
PHYSICS – CHAPTER 35 – CIRCUITRY ACTIVITY
In this activity, we will be looking at Ohm’s Law and Equivalent Resistance. You will construct basic
circuits using hands-on materials and a computer simulation; and you will measure and calculate values for
voltage, current, and resistance. The goal of this activity is to reinforce your knowledge of basic circuitry as
well as look at the mathematical relationships between basic electrical values.
PART V – Review Questions
a. What are some of the basic characteristics of a series circuit? (Example: the current is the same
everywhere in the circuit)
b. What are some of the basic characteristics of a parallel circuit? (Example: the voltage is the same
across each branch of the parallel portion of the circuit)
c. What is the formula for Ohm’s Law?
d. What are the formulas for calculating equivalent resistance?
e. Name the circuit element that is depicted by each of the following symbols:
PART VI – Building Circuits
For the following circuit, construct a model of the circuit described. Once your model has been
approved by the teacher, sketch an accurate schematic diagram in the space provided. Then use the
meters to answer the questions that follow.
1) Construct the follow circuit using a battery, a SPST switch, and three light bulbs. Place two light bulbs in
parallel. This parallel branch should be place in series with the other light bulb, the battery, and the switch.
a. Use the voltmeter to measure the voltage across the battery. Remember that the voltmeter is
placed in parallel in order to get an accurate measurement.
b. Use the voltmeter to measure the voltage across each of the individual light bulbs:
LIGHT BULB NUMBER
VOLTAGE (volts)
1 (in series)
2 (in parallel branch)
3 (in parallel branch)
c. How do the voltages in the parallel branch compare?
d. What is the sum of the voltages of series light bulb and one of the parallel light bulbs? How does
this compare to the voltage across the battery? Do your results make sense?
e. Use the ammeter to measure the current at the following locations. Remember that the ammeter
must be placed in series in the circuit in order to get an accurate measurement.
CIRCUIT LOCATIONS
CURRENT (amps)
Immediately after the battery
At light bulb 1 (in series)
At light bulb 2 (in parallel branch)
At light bulb 3 (in parallel branch)
f. How do your measurements compare?
g. What is the sum of currents of the light bulbs in the parallel branch? How does this answer
compare to the values in your chart?
h. What can you conclude about the nature of current in a circuit?
i. Use the multimeter to measure the resistance in the following locations:
CIRCUIT LOCATIONS
RESISTANCE (ohms)
Across light bulb 1 (in series)
Across light bulb 2 (in parallel branch)
Across light bulb 3 (in parallel branch)
Across entire parallel branch
Across entire circuit
j. Use your resistance measurements for the individual light bulbs and the equations to calculate the
equivalent resistance of the circuit. How does your calculate answer compare to your measured
value?
k. Do your values for voltage (across battery), current (immediately after battery), and equivalent
resistance (across entire circuit) fulfill Ohm’s Law? Show your work and explain.
PART VII – Building Circuits Using the Computer Simulation
Follow the directions for each of the following circuits. Print off a copy of each schematic you create.
After printing the copy, write the question number on the paper. Attach the copy to this worksheet.
1) Create a circuit that uses a 12-V battery. The battery should be in series with a switch, an 8- resistor,
and a parallel branch. In the parallel portion, on branch should have a 2- resistor and a 5- resistor in
series. The other branch should have a 6- resistor. Place the voltmeter in the schematic to show the
voltage across the battery. Place ammeters in the circuit to show the current at all relevant points in the
circuit. Show the values on the schematic as well.
a) Use Ohm’s Law to calculate the equivalent resistance of the circuit.
b) Use the equations to calculate the equivalent resistance of the circuit. How do your answers
compare?
2) Create a circuit that uses a 30-V battery. The battery should be in series with a switch, and a parallel
branch. In one of the branches, there should be a 2- resistor, a 9- resistor, and 4- resistor in series. The
other branch should begin with a 3- resistor. That resistor should be in series with an additional parallel
branch. One of these branches should have a 5- resistor and the other should have a 10- resistor. Place
the voltmeter in the schematic to show the voltage across the battery. Place ammeters in the circuit to show
the current at all relevant points in the circuit. Show the values on the schematic as well.
a) Use Ohm’s Law to calculate the equivalent resistance of the circuit.
b) Use the equations to calculate the equivalent resistance of the circuit. How do your answers
compare?
3) Use the simulator to create a circuit that meets the following requirements:
a. A 24-V battery
b. A switch
c. A current of 0.6 A
d. An equivalent resistance of 40 
e. At least three resisters with at least one parallel branch.
f. The voltage and resistances should be labeled on the schematic for each component.
g. Use the ammeter feature to display the current coming out of the battery.
4) Use the simulator to create a circuit that meets the following requirements:
a. A 48-V battery
b. A switch
c. A current of 2.0 A
d. An equivalent resistance of 24 
e. At least four resisters with at least two parallel branches.
f. The voltage and resistances should be labeled on the schematic for each component.
g. Use the ammeter feature to display the current coming out of the battery.
PART VIII – Conclusions
a. In your opinion, do Ohm’s Law and the equations for equivalent resistance work well in real life
situations? Explain.
b. What might be some reasons why the calculated values for voltage, current, and resistance do not
always match the measured values?