Science 9 Unit D: Electrical Principles
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Science 9 Lesson Plan: Electricity and Magnetism
Subject: Science 9
Unit D: Electrical Principles
Date: Mon March 23
Teacher: Grace Martin
Topic 6: Motors and Generators
Time: 90 min
GLO 1: Investigate and interpret the use of devices to convert various forms of energy to electrical energy,
and electrical energy to other forms of energy
Specific Outcome 1.4 construct, use and evaluate devices for transforming mechanical energy into electrical
energy and for transforming electrical energy into mechanical energy
Specific Outcome 1.5 modify the design of an electrical device, and observe and evaluate resulting changes
(e.g., investigate the effect of changes in the orientation and placement of magnets, commutator and armature
in a St. Louis motor or in a personally-built model of a motor)
Lesson Objectives: By the end of the lesson, students will be able to:
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Explain the difference between a generator and a motor

Describe an electromagnet
Materials/Resources:
ScienceFocus 9, Topic 6: Motors and Generators (page 300-308)
http://www.learnalberta.ca/content/seetbsf9/html/ScienceFocus9/default.html
Science in Action 9, 3.2 Energy Transformations Involving Electrical and Mechanical (p 324)
http://www.learnalberta.ca/content/seetb/html/unit_d/index.html?page=319
Gizmo: http://www.learnalberta.ca/content/secs/html/electrical_principles_and_technologies/BuildingAMotor/index.html
Powerpoint
Lesson Procedure:
9As: Monday March 23rd Notes (30min) and assignment handout (15min)
Tuesday March 24th Exploratory stations (30min) and assignment handout (15min)
9Bs: Monday March 23rd Notes for the first 30 minutes. Exploratory stations for 30 minutes.
Assignment handout for 30 minutes.
Notes: Review electricity and magnetism connection. PowerPoint slides for Generators and
Motors including AC and DC.
Assignment Handout: Generators and motors questions
Assignment: Generators and motors handout
Motor Gizmo:
http://www.learnalberta.ca/content/secs/html/electrical_principles_and_technologies/BuildingAMotor/index.html
Assessment:
Filling out assignment worksheets/handouts
Science 9 Unit D: Electrical Principles
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Exploratory Stations Lab Report: Electricity, Magnetism, and Mechanical Energy
Station A: Generators (5 min)
Instructions: Turn the crank on the handheld device to light the bulb.
How are you generating electricity to power the bulb?
Draw a diagram of how a generator works. Label commutator and armature.
Station B: Motors (5 min)
Instructions: Plug in the motor into an electrical power source.
How is the electricity causing movement?
Draw a diagram of how a motor works. Label commutator and armature.
Station C: Electromagnets (10 min)
Hypothesis: What size of nail and amount of wire coils will produce the greatest
magnetic field?
Instructions: Hook up the electromagnets to the battery power source. Move the
compass toward the nail. Does the compass needle deflect?
Can you pick up iron filings with the nail end?
How is the number of wire coils related to the strength of the magnetic field?
Station D: Piezoelectric crystal (5 min/break)
When a piezoelectric crystal is squeezed or compressed it converts _________________________
energy into _______________________ and _______________________ energy.
Station E: Visualizing a magnetic field (5 min)
Instructions: Place a covering over a bar magnet and shake iron filings onto it. Draw the
pattern.
Science 9 Unit D: Electrical Principles
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Motors and Generators: Fill in the blanks. Use words more than once or not at all.
Electric
Magnetic
Magnet
Wire
Attract
Stronger
Electrical
Coil
Repel
Weaker
Battery
Mechanical
Poles
Electrons
Spinning
Motor
Generator Electromagnet
1. When electricity runs from a conducting wire, especially when it is in a cylindrical
coil, a ________________________ field is created.
2. A permanent magnet can either ___________________ or ___________________ the wire or
current-carrying armature.
3. You can improve a motor in the following ways: more turns of the _________________, a
more powerful ________________________, or a more powerful ________________________.
4. Iron filings overtop of a bar ________________________ can show field lines between the
north and south poles.
5. Electricity and magnetism related because flowing ________________________ produce a
magnetic field.
6. Motors convert ________________________ energy to ________________________ energy.
7. A simple ____________________ uses the flow of electricity through a wire loop, or
armature, near a stationary magnet, to rotate the loop/armature.
8. When a magnetic field is moved toward a conducting wire, an _______________________
current can be induced.
9. Electricity and magnetism are also related because ________________________ magnets
can produce electricity.
10. Generators convert ________________________ energy to ________________________ energy.
11. A simple _______________________ uses a force input of motion to rotate the armature,
or loop of wire inside of a magnet. The spinning wire begins to conduct electricity.
12. North and south poles form on opposite sides of an ________________________ when an
electric current is passed through the coils wrapped around a metal rod.
13. You can turn an iron nail into an electromagnet by wrapping a _________________ of
wires around it and hooking it up to a power source, such as a battery.
14. An alternating current changes directions of electron flow in the ___________________;
whereas direct current electrons flows in one direction down a ___________________.
Science 9 Unit D: Electrical Principles
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Topic 6 Generator and Motor Notes
AC Generators (also called Alternators)

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
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
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Alternating Current
External force rotates the coil
Coil of wire rotates inside of a stationary magnetic field
Most generators use electromagnets instead of permanent magnets
As coil’s wires rotate inside the field, electrons move
AC generators produce electricity that changes directions
After one half-rotation of the coil, each side passes near the opposite
pole of the magnet, and the electrons move in the opposite direction
Benefit: easy to increase or decrease voltage
Parts:
 Armature: loop of rotating wire near the magnet
 Commutator: device for reversing the direction of electric current.
Connected to the armature of a motor or generator, through which electrical
connection is made and which ensures that the current flows as direct current.
DC Generators (also called Dynamo)
 Direct Current in only one direction
 Electrons always flow in same direction from armature to
commutator and back to armature
Electric Motors
• Convert electrical energy to mechanical energy
• Motor uses electricity flowing through armature (coil) to make coil of wire spin
in magnetic field. Creates an electromagnet.
DC Motor
AC Motor
 In large appliances
 Rotor: rotating core of
conducting wires
 Stator = electromagnet
 Attraction/repulsion of
stator/rotor cause rotor to spin
Science 9 Unit D: Electrical Principles
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Science 9 Unit D: Electrical Principles
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Topic 6 Review Questions
1. What is the difference between AC and DC? Describe ways each is produced.
2. Describe the function of the electric motor parts: split ring commutator,
armature, and brushes?
3. What is a two-pole coil of wire in an electric motor called?
4. What is an electric generator?
5. What is the difference between an alternator and a dynamo?
6. What are the rotor and stator and what device uses them?
Topic 6 Study Guide
I need to know about…
(1) How electricity and magnetism are related
 Electromagnets: created when current is passed through a coil of wire wrapped
around an iron rod and north and south poles form on either end of the wire
 Electricity is the flow of electrons (electric current)
(2) Devices for transforming mechanical energy to electrical energy
 Generators: potential difference (voltage) is induced in a wire when there is
relative motion between the wire and a nearby magnet. When the wire is
connected in circuit the potential difference causes induced current to flow.
 Power plant turbines provides enough force to turn the generator’s coil of wires
 Difference between AC and DC generators and benefits of AC for transmission
(3) Devices for transforming electrical energy to mechanical energy
 Motors use electromagnets to create motion.
 Difference between AC and DC motors
 Parts: commutator, armature, rotor, stator, brushes
(4) How changes in design affect an electrical device
 What happens when you:
o Use more coils or more powerful battery (higher voltage) for electromagnets?
o Change the orientation and placement of magnets in a motor?
o Have a dirty commutator? Have a clean commutator?
Science 9 Unit D: Electrical Principles
o Change the orientation of the armature in a motor?
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