AGRISCIENCE EXERCISE
Physical Science in Agriculture
Teacher Guide
Key Concept:
Electricity and Electronic Systems
Sub-Concept:
Electric Circuits
Agricultural Context:
Basic electronic principles are applied in common
agricultural equipment
Exercise:
Determining Total Resistance in Series and Parallel
Circuits
Goals:
1. Describe the relationship between the resistance of
individual loads and the total resistance in series,
parallel, and series-parallel circuits
Materials:
(per group)
Digital multimeter (DMM)
Calculator
3 resistors of different resistance values
Insulated lead wires with alligator clip connectors
Masking tape
References:
Refer to any basic electricity or high school physics textbook
for further information
Teacher Preparation Notes/Conducting The Activity
1. Divide the class into pairs of students, and provide each with a data sheet
and the necessary materials for this exercise.
2. Instruct the students to complete the activity as directed on their data sheets.
You may wish to monitor their progress as they work; however, it is
suggested that the students be left to follow the instructions and complete the
activity on their own.
3. Once all groups have completed the exercise, discuss the answers to the
discussion questions as a class. Be sure to make note of the practical
agricultural applications of the principles demonstrated.
Procedures for Conducting Actvitiy
1. Gather all materials listed.
2. Use the resistance function of the DMM to determine the resistance of each
resistor. Write these resistance values on pieces of masking tape and attach
the tape to the appropriate resistor.
3. Connect the resistors in series as shown below:
4. Record your estimate of the total resistance of this series circuit below:
Expected Total Resistance (Series Circuit) = __________ Ohms
5. Determine the actual total resistance of your series circuit by connecting the
DMM (set for resistance) in the circuit as shown:
Actual Total Resistance (Series Circuit) = ____________ Ohms
6. Connect the resistors in parallel as shown below:
7. Record your estimate of the expected total resistance of this parallel circuit:
Expected Total Resistance (Parallel Circuit) = ____________ Ohms
8. Determine the actual total resistance of this parallel circuit by connecting the
DMM (set for resistance) in the circuit as shown below:
Actual Total Resistance (Parallel Circuit) = ______________ Ohms
9. Connect the resistors to form a series-parallel circuit as shown below:
10. Record your estimate of the expected total resistance of this parallel circuit.
Expected Total Resistance (Series-Parallel Circuit) = __________ Ohms
11. Determine the actual total resistance of this series-parallel electrical circuit
(set for resistance in the circuit as shown below:
Actual Total Resistance (Series-Parallel Circuit) = ____________ Ohms
12. Disassemble the circuit and return your supplies and equipment to their
proper locations
13. Answer the following discussion questions:
a. Describe the difference in the total resistance of series and parallel
electrical circuits.
b. Develop an equation that can be used to predict the total resistance of
a series circuit.
c. Develop an equation that can be used to predict the total resistance of
a parallel circuit.
d. How are house lights wired (series or parallel)? Why is this?
e. Describe how to estimate the total resistance of a series-parallel
circuit.
AGRISCIENCE EXERCISE
Physical Science in Agriculture
Student Guide
Key Concept:
Electricity and Electronic Systems
Sub-Concept:
Electric Circuits
Agricultural Context:
Basic electronic principles are applied in common
agricultural equipment
Exercise:
Determining Total Resistance in Series and Parallel
Circuits
Goals:
1. Describe the relationship between the resistance of
individual loads and the total resistance in series,
parallel, and series-parallel circuits
Materials:
(per group)
Digital multimeter (DMM)
Calculator
3 resistors of different resistance values
Insulated lead wires with alligator clip connectors
Masking tape
References:
Refer to any basic electricity or high school physics textbook
for further information
Procedures for Conducting Actvitiy
1. Gather all materials listed.
2. Use the resistance function of the DMM to determine the resistance of each
resistor. Write these resistance values on pieces of masking tape and attach
the tape to the appropriate resistor.
3. Connect the resistors in series as shown below:
4. Record your estimate of the total resistance of this series circuit below:
Expected Total Resistance (Series Circuit) = __________ Ohms
5. Determine the actual total resistance of your series circuit by connecting the
DMM (set for resistance) in the circuit as shown:
Actual Total Resistance (Series Circuit) = ____________ Ohms
6. Connect the resistors in parallel as shown below:
7. Record your estimate of the expected total resistance of this parallel circuit:
Expected Total Resistance (Parallel Circuit) = ____________ Ohms
8. Determine the actual total resistance of this parallel circuit by connecting the
DMM (set for resistance) in the circuit as shown below:
Actual Total Resistance (Parallel Circuit) = ______________ Ohms
9. Connect the resistors to form a series-parallel circuit as shown below:
10. Record your estimate of the expected total resistance of this parallel circuit.
Expected Total Resistance (Series-Parallel Circuit) = __________ Ohms
11. Determine the actual total resistance of this series-parallel electrical circuit
(set for resistance in the circuit as shown below:
Actual Total Resistance (Series-Parallel Circuit) = ____________ Ohms
12. Disassemble the circuit and return your supplies and equipment to their
proper locations
13. Answer the following discussion questions:
a. Describe the difference in the total resistance of series and parallel
electrical circuits.
b. Develop an equation that can be used to predict the total resistance of
a series circuit.
c. Develop an equation that can be used to predict the total resistance of
a parallel circuit.
d. How are house lights wired (series or parallel)? Why is this?
e. Describe how to estimate the total resistance of a series-parallel
circuit.