University of Arkansas - AgriScience Project

AGRISCIENCE EXERCISE

PHYSICAL SCIENCES IN AGRICULTURE

Key Concept: Electricity and Electronic Systems

Sub-Concept: Electric Circuits

Agricultural Application: Basic electronics principles are applied n common agricultural equipment.

Exercise: Construct a DC Electric Motor

Applied Principle(s): Basic principles of electricity

Goals:

  1. Construct a simple electric motor.
  2. Explain how a DC motor works.


Materials:



Reference: Attached information sheet

Procedures for Conducting the Activity:

1. Divide the class into small groups of no more than 3 students each.

2. Provide each student with an instruction/data sheet, and allow the class time to read the entire activity and attached information sheet before proceeding.

3. Provide each group with the necessary materials.

4. Allow the students to proceed through the activity, providing assistance as necessary.

5. When all groups have finished, discuss the activity questions and results as a class. Discuss the practical applications of the knowledge gained through the activity.





AGRISCIENCE EXERCISE

- Constructing a DC Electric Motor -

Student Data/Instruction Sheet

1. Read the attached information sheet before proceeding through this exercise, to gain a better understanding of the relationship between the components of Ohm's Law.

2. Secure the following equipment supplies:



3. Wrap the enamel insulated wire into a coil. Occasionally wrap the wire around the coiled loops to prevent the coil from coming apart. (The coil will form the armature of your motor.)

4. Bring the two wire ends out of the coil (armature) 180 degrees apart. Both ends should stick out approximately two inches.

5. Use the utility knife to carefully scrape the insulation off of both the wire ends of the armature.

6. Make two support bearings out of the No. 18 copper wire. The bearings should support the armature just slightly above the magnet.

7. Secure the bearings to the wooden platform with the tape.

8. Mount the armature on the bearings.

9. Place the magnet on the wooden platform underneath the armature.

10. Connect one end of each electrical lead to a terminal of the 6-volt dry cell battery.

11. Connect the free end of each electrical lead to a different support bearing.



12. The completed electric motor without battery is illustrated below.





















13. If necessary, gently spin the armature to "start" the electric motor.





14. What causes the armature to rotate?









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