Resistance in Series Circuits

Name ______

You are designing a Holiday light and Santa display at your house. You need to decide what you may want to place in series and what you may want to place in parallel. First you must discover the attributes of both. You will do this using a computer simulation.

Goals:

Correctly place voltmeters and ammeters in a series circuit.

Find the voltage and amperage in series circuits.

Determine which is constant in a series circuit, voltage or amperage.

Go to
Click “Run now.”
Make a series circuit using three resistors and a battery. Remember the series circuit is circular with only one path for electricity.

1)Add an ammeter between each resistor and the resistors and the battery

2) Measure voltage with a voltmeter over each of the resistors.

3)Turn on Show Values so you see the resistor values

4)Change the resistor values by right clicking the resistor. Make the resistors at least 10 Ohms different!

5)Record the resistor values, voltages and the amps in the table below.

6)Unhook one of the resistors from the circuit. What happens to the amps throughout the circuit? Why?

7)Discuss with another student, what conclusions can be drawn from this data? (record conclusions)

Resistor size (R) in Ohms / Voltage (V) / Amperage (I)
In amps / V/I in Ohms

Resistor 1

Resistor 2
Resistor 3 /
Source / R1+R2+R3= / V1+V2+V3=

Questions

1) How close were your resistor size and the V/I resistor calculation you found using Ohm’s Law?

2) When placing a voltmeter in a circuit, does it go in series or parallel?

3) When placing an ammeter in a circuit, does it go in series or parallel?

4) What conclusions can you draw from the readings on the voltmeters?

5) What conclusions can you draw from the readings on the ammeters?

6) Which best describes a series circuit? Circle all that apply:

a) Vs = V1 + V2 + V3d) Vs = V1 = V2 = V3

b) It = I1 + I2 +I3e) It = I1 = I2 =I3

c) Rt = R1 + R2 +R3f) Rt = R1 = R2 =R3

7) If the resistors were replaced with light bulbs, and you unhooked a light, what would happened? If a light burns out the same effect will be seen. How would this affect your holiday display?

Resistance in Parallel Circuits

Goals:

Correctly place voltmeters and ammeters in a parallel circuit.

Find the voltage and amperage in parallel circuits.

Determine which is constant in a parallel circuit, voltage or amperage.

1) Reset the screen to remove all of the series circuit.

2) Make a parallel circuit using three resistors and a battery.

3) Add a voltmeter over each of the resistors.

4) Add an ammeter in line with each resistor.

5) Change the resistor values by right clicking the resistor. Make the resistors at least 10 Ohms different!

6) Record the resistor values, voltages and the amps in the table below.

7) Unhook one of the resistors from the circuit. What happens to the current at the other resistors? Why?

8)Discuss with another student, what conclusions can be drawn from this data? (record conclusions)

Resistance / Amperage / Voltage

Resistor 1

Resistor 2
Resistor 3
Source / A1+A2+A3=

Questions

1) What conclusions can you draw from the readings on the voltmeters?

2) What conclusions can you draw from the readings on the ammeters?

3) What are the advantages to placing lights and motors in parallel?

4) Which best describes a parallel circuit? Circle all that apply:

a) Vs = V1 + V2 + V3d) Vs = V1 = V2 = V3

b) It = I1 + I2 +I3e) It = I1 = I2 =I3

1 1 1 1

c) Rt = R1 + R2 +R3f) Rt = R1 = R2 =R3

5) Compare and contrast a parallel and a series circuit. How are they alike? How are they different?

6) Will you use series or parallel to wire your holiday display?

Applying the skills

Complete the following tables using Ohm’s Law and circuit calculations.

SERIES

Resistor size (R) in Ohms / Voltage (V) / Amperage (I)
In amps

Resistor 1

/ 15 ohms / .02 amps
Resistor 2
Resistor 3 / .7 volts
Source / RT / VT = 1.5 volts / IT

PARALLEL

Resistance / Amperage / Voltage

Resistor 1

/ 10 ohms
Resistor 2 / .3 amps / 6 volts
Resistor 3 / 20 ohms
Source / RT / IT / VT