1. Topic 6: Generators and Motors
Science 9 with Mrs M
Please take off your hats and hoods

2. Iron Man’s Electromagnet hooked up to a car battery
Electromagnet kept shrapnel from entering his heart

3. Power Plant Turbine -> Generator
Topic 6 Generators and Motors
Power Plant Turbine -> Generator
The turbine provides enough force to turn the generator’s coil of wires

4. Topic 6 Generators and Motors NOTES
Electric Generator
Device that converts mechanical energy into electric energy
Works on principle of electricity and magnetism, or electromagnetism

5. Electricity and Magnetism are related
Topic 6 Generators and Motors NOTES
Electricity and Magnetism are related N S

6. How do we know? Compass needle turns when near electric field
Topic 6 Generators and Motors NOTES
How do we know?
Compass needle turns when near electric field
With more electricity there is a stronger needle deflection = stronger magnetic field
Reverse the electric current and you reverse the direction of the magnetic field
Stop the current = stop the magnetic field

7. Topic 6 Generators and Motors NOTES
Electromagnet
When current is passed through a coil of wire wrapped around an iron rod an electromagnet is created
North and south poles form on either end of the wire
More coils = stronger magnet

8. Magnetized Material Water has a dipole (North and South)
Topic 6 Generators and Motors
Magnetized Material
Water has a dipole (North and South)
Alignment of “poles” is similar to
the alignment of charges.

9. MRI works on this principle
Topic 6 Generators and Motors
MRI works on this principle
(Magnetic Resonance Imaging)

10. Earth has a magnetic field

11. The human heart’s electrical impulses create a magnetic field

12. Example of an electromagnet: Maglev Trains

13. How are electricity and magnetism related?
Topic 6 Generators and Motors
How are electricity and magnetism related?
Electricity and magnetism related because flowing electrons produce a magnetic field.
Electricity and magnetism are ALSO related because spinning magnets can produce electricity.

14. Generators
Electricity is induced when there is relative motion between the wire and a nearby magnet.

15. https://www.youtube.com/watch?v=d_aTC0iKO68 Motor: Generator:
Topic 6 Generators and Motors
Electricity and magnetism are related: (1) flowing electrons produce a magnetic field (2) spinning magnets can produce electricity
Motor:
electricity -> mechanical energy
Generator:
magnet -> mechanical force -> electricity

16. Electricity and magnetism are related: (1) flowing electrons produce a magnetic field (2) spinning magnets can produce electricity
Motor:
electricity -> mechanical energy
Generator:
mechanical force -> electricity

17. AC Generators (also called Alternators)
Topic 6 Generators and Motors
AC Generators (also called Alternators)
Turbine rotor rotates the coil (armature) inside magnet
Electrons move in coil

18. AC: Alternating Current
Topic 6 Generators and Motors
AC: Alternating Current
AC: Alternating Current
Electrons move in the opposite direction every half rotation of coil

19. AC Generator Parts
WRITE THIS DOWN
Has a rotor (spinning shaft), coil (armature), field magnet, and brushes (to connect circuit)
AC Generators do NOT have a commutator

20. AC Current Positive and negative show different directions
Topic 6 Optional note-taking slide
AC Current
Positive and negative show different directions

21. Benefits of AC current Easy to increase/decrease the voltage
Topic 6 Generators and Motors
Benefits of AC current
Easy to increase/decrease the voltage
This helps set up voltage for power line transmission (more in Topic 7)

22. Parts Armature: loop of rotating wire near the magnet
Topic 6
Parts
Armature: loop of rotating wire near the magnet
Commutator: device for reversing the direction of electric current in DC generators
Brushes touch spilt metal rings

23. DC Generators (also called a dynamo)
Topic 6
DC Generators (also called a dynamo)
Current in only one direction

24. Topic 6
DC Generators
Electrons always flow in same direction from armature to commutator and back to armature
Position 3 both electron flow and commutator connection have changed direction

25. Electric Motors Convert electrical energy to mechanical energy
Topic 6
Electric Motors
Convert electrical energy to mechanical energy
Uses electricity flowing through armature (coil) to make coil of wire spin in magnetic field
Creates an electromagnet

26. Exploratory Stations Generator Motor Electromagnets
Topic 6 Generators and Motors
Exploratory Stations
Generator
Motor
Electromagnets
Piezoelectric crystal
Bar magnet’s field lines

27. Video on generators and motors http://study

28. What’s the difference?
"AC/DC" on a sewing machine = alternating current/direct current electricity.

29. AC DC Cheaper Self-starting Speed needs to be externally controlled
More efficient
Cost more
Better for long distance transfer
Used in: electronics like cell phone and tablet, hybrid and electric cars DC
Cheaper
Self-starting
Speed needs to be externally controlled
Used in: car ignition, leaf blower, RVs

30. DC motors
Ignition

32. AC motor
Car alternator to recharge battery when engine is running

33. AC Motors Fans, elevators, pumps, etc
Good for hard systems that need a lot of upfront power
AC can be used for long periods of time

34. AC vs DC Motors DC Benefit: self-starting (like ignition)
DC drawback: Speed needs to be externally controlled
AC benefit: can be used in variant situations
AC drawback: need starter

35. AC Motors In large appliances
Topic 6
AC Motors
In large appliances
Rotating core (rotor) of conducting wires
Stator = electromagnet
Attraction/repulsion of stator/rotor cause the rotor to spin

36. DC Motor Momentum keeps armature swinging
Topic 6
DC Motor
Momentum keeps armature swinging
Commutator reverses current direction so armature reverses polarity to continue swinging
North pole attracted to south causes rotation

37. Links Motors and Generators (6 min)
Commutators (4 min)

38. Iron Man’s Electromagnet hooked up to a car battery
Electromagnet kept shrapnel from entering his heart

39. Study Time
How does a generator works to create electricity? Generators work by moving the coil/armature, through a magnetic field. When the coil of wire is moved past permanent magnets, electricity is produced in the wire (electromagnetic induction).

40. Study Time
Describe how a motor works and label its parts:

41. AC Generator powers an AC Motor

42. Study Time
What two actions can a permanent magnet do to a current carrying armature?
A permanent magnet can either attract or repel a current-carrying wire.

43. Study Time
Suggest and describe ways that you could improve your motor.
Use a larger battery, use more turns of wire, or use a more powerful magnet.
A motor created voltage as the shaft is turned. What is this evidence of?
Electromagnetic induction

44. Study Time
Positions 1 and 3 provide current (HINT: electric current is flow of electrons)
Positions 2 and 4 have no current flowing

45. Facts about Electricity and Magnetism:
Electricity in a coil of wires can create a magnetic field
A spinning magnet can induce an electric current
There are two kinds of electric charges—positive and negative—and two kinds of magnetic poles—north and south.
Unlike charges or poles attract; like charges or poles repel.
Only certain materials can be charged or magnetized.

46. Facts about Electricity and Magnetism:
To produce an electric current you need a conductor connected to a closed circuit, and you need relative motion between the coil and magnet.
When the electric current is reversed the electromagnet’s polarity flips.
Electromagnetic induction occurs when you create an electric current by moving the armature inside the magnet.

47. Study Time What is an electromagnet?
What happens when you rotate the armature inside a magnet?
What is the definition of a commutator?
AC means alternating current
DC means direct current

48. Facts about generators
They convert mechanical energy to electrical energy
A DC generator has a commutator that only allows current to flow in one direction through a circuit.
An AC generator doesn’t have a commutator. An AC generator has a rotor, armature, brushes, and a field magnet.
You can increase the electrical current in a generator by using more turns of the coil of wire in the armature, or by using a stronger magnet

49. Facts about motors Motors convert electrical to mechanical energy
Motors and generators rely on the same electromagnetic principles
Motors are constructed in the same way that generators are
Motors are generators acting in the reverse
The attraction and repulsion between the magnetic poles of the armature and the field magnet can the armature to spin when current passes through coils

50. Review Game 4 questions of 4 corners 12 questions of team trivia

51. Four Corners Individual, 16 questions (or we can do a blend)
No running!
“answer” by moving to a corner of the classroom (A B
D C)

52. What is the difference between AC and DC?
AC is asking commutator
AC is alternating commutator
DC is direct current
DC is during connection D C

53. Motors: Convert electricity to motion Are used to create currentB
Motors:
Convert electricity to motion
Are used to create current
Convert motion to electricity
Require a rotor D C

54. Which of the following is an electromagnet?B A D C

55. What can create a magnetic field?B
What can create a magnetic field?
A spinning field
Electricity in a coil of wires
A spinning coil
A commutator D C

56. Gopher Get Down 4 teams, 4 questions each
Questions rotate between teams
If you think you know the answer, stand up
You can “cheat” and stand if you don’t know, but be prepared to risk being called on!

57. Which will induce an electric current?B D C

58. Which opposites are electric?B
Which opposites are electric?
North and South Pole
Magnetic polarities
Positive and Negative charges
Positive and Negative poles D C

59. Which is an AC generator?B C D

60. What can be magnetized? Wood Plastic rotor shaft Commutator Iron A B D

61. What do you need to have for an electric current?B
What do you need to have for an electric current?
conductor connected to a closed circuit
moving magnetic field
terminals
coils D C

62. Which is an AC generator?B C D

63. What can induce an electric field?B
What can induce an electric field?
A spinning magnet by a wire
An armature of wires by a battery
A spinning coil by a turbine
A set of spinning brushes D C

64. What best describes a commutator?
A circular object
A circular coil of wires
Reverses direction of electric current
Connects the flow of electrons to the circuit D C

65. What is electromagnetism?B
What is electromagnetism?
A relationship between electrons and iron
Relation between electricity and magnetism
Coil of wiring inducing an electric current
Like charges repel and opposites attract D C

66. How can you improve a generator?B
How can you improve a generator?
Larger magnet
More current
More slip rings
Faster commutator D C

67. How can you improve a motor?B
How can you improve a motor?
Smaller magnet
More input motion
More turns of the coil of wire
Larger brushes D C

68. A B
Which does not belong? D C