1. TEST REVIEW ELECTRONS Electricity begins with Electrons. ATOMS
U3e-L1
TEST REVIEW ELECTRONS
Electricity begins with Electrons.
ATOMS
Electron cloud surrounds an atom’s nucleus
Nucleus is made of
Electrons – negative charge
Protons – positive charge
Neutrons – zero charge (neutral)
Protons and Neutrons

2. ELECTRONS move from negative ( - ) terminal to positive ( + ) terminal
U3e-L1
REVIEW CIRCUITS
The paths that electrons travel are called circuits.
Circuits must consist of three things:
ELECTRONS move from negative ( - ) terminal to positive ( + ) terminal
Power Source – with positive and negative terminals.
Conductor – the path the electrons travel along.
Load – this is what the electricity powers (e.g. motor, light bulb)
LOAD

3. REVIEW CONDUCTORS Which material has free electrons, Wood or Metal?
U3e-L1
REVIEW CONDUCTORS
Conduct – from Latin for “leading, guiding.”
A conductor is any material that allows electrons to easily flow.
Remember the atom:
Conductors’ electrons are not tightly bound to the atom.
Conductors have free electrons.
Which material has free electrons, Wood or Metal?
Metals conduct electricity easily.

4. Review INSULATORS Insulate – from Latin for “separate, divided.”
U3e-L1
Review INSULATORS
Insulate – from Latin for “separate, divided.”
An insulator is any material that impedes the flow of electrons.
Remember the atom:
Insulators’ electrons are tightly bound to the atom.
Because the electrons don’t move, insulators cannot conduct electricity very well, if at all.
Which material has bound electrons, Wood or Metal?
Wood does not have free electrons.

5. Air Copper Free-electrons Cotton Aluminum Bound Electrons Silver Gold
U3e-L1
Air
Copper
Free-electrons
Cotton
Aluminum
Bound Electrons
Silver
Gold
Wood
Plastic
INSULATOR
Cotton
Wood
Plastic
Air
BOUND ELECTRONS
CONDUCTOR
Copper
Gold
Silver
Aluminum
FREE ELECTRONS

6. U3e-L1
Review Joule’s Law
James Joule (1818 – 1889) – showed that heat and electrical energy are interchangeable.
Joule’s Law:
Power = Voltage x Current
P = V I
Watts = Volts x Amperes

7. U3e-L1
Review Ohm’s Law
George Ohm (1789 – 1854) – a high school and university mathematics instructor
Discovered ~1827
Voltage = Current x Resistance
V = I R
What are the units of this formula?
Volts = Amperes x Ohms

8. U3e-L2
TERMINOLOGY
Current (I) – the motion of electrons from one atom to the next in a material.
In our circuit, electrons flow from ___________ terminal to the ___________terminal.
This motion of electrons through our conductor (wire) is considered current (like water through a pipe).
Materials that resist current are
called ___________.
Materials that provide
a path for current are called
___________.
Current is measured in AMPERES (Amps)
NEGATIVE
POSITIVE
LOAD
INSULATORS
CONDUCTORS

9. U3e-L2
Review TERMINOLOGY
Voltage (V) – the electric potential between two points of opposite charge.
Voltage is the potential energy of the electrical power source.
Voltage is measured in Volts (V).

10. Review Electric Schematics
U3e-L3
Review Electric Schematics
What is a schematic?
Which of the following is a schematic?
A schematic is a diagram that represents the elements of a system without using realistic pictures

11. U3e-L8
Review March 04, 2010
DRILL
What does the following schematic symbol represent?
How many volts are typical in a residential electrical outlet?
What do graphs of DC and AC power sources look like? Why?
DC Power Supply
AC Power Supply
120 volts

12. Review Problems – Joule’s Law
U3e-L2
Review Problems – Joule’s Law
Write the given information:
V = 144 Volts
P = 20,000 Watts I = ?
Sketch a schematic diagram of the circuit:
Start with power source
Add conductors
Add load
Add current +
P = 20,000 W
V = 144V -
I = ?

13. Review Problems – Joule’s Law
U3e-L2
Review Problems – Joule’s Law
Write the given
information:
V = 144 Volts
P = 20,000 Watts I = ?
Rearrange, Substitute, and Solve
Sketch a schematic diagram of the circuit:
V = 5V
I = .7A - +
R = ?
P = V x I
I = 20,000W / 144V
R = A
I = P / V

14. Review Resistance Calculations
U3e-L3
Review Resistance Calculations
Resistors in series are added: R1 R2 R3
Total Resistance:
R = R1 + R2 + R3 T

15. Review Resistance Calculations
U3e-L3
Review Resistance Calculations
Resistors in parallel: add their reciprocals R1 R2 R3
Total Resistance: =
R R1 + R2 + R3 T

16. Review ELECTRIC MOTORS
U3e-L8
Review ELECTRIC MOTORS
What is a schematic?
How would a schematic which includes an electric
motor look?
A schematic is a diagram that represents the elements of a system without using realistic pictures.
Switch = Commutator
Motor
V = 9V I

17. Review ELECTRIC MOTORS
U3e-L8
Review ELECTRIC MOTORS
Now that you know what switches look like in electrical schematics, draw an electrical schematic for a lamp plugged into a wall outlet.
Remember that AC power supplies look like in electrical schematics.

18. Review ELECTRIC MOTORS
U3e-L8
Review ELECTRIC MOTORS
120 V
Lamp

19. U3e-L2
Review TERMINOLOGY
Resistance (R) –a measure of the degree to which an object opposes an electric current through it .
Resisting an electric current often generates heat.
This is the principle behind how light bulbs work.
Resistance is measured in Ohms (W – the Greek letter Omega)

20. Review Electric Motors
U3e-L8
Review Electric Motors
Michael Faraday ( )
London, England.
Physicist and Chemist
First person to successfully create an electric motor.
Discovered that electric currents create a magnetic field, and vice versa.

21. Review ELECTRIC MOTORS
U3e-L8
Review ELECTRIC MOTORS
Electric motors are used everyday in many ways.
A motor’s purpose is to turn electrical energy into mechanical energy.
Motors work on simple principles of magnetism:
Opposite poles _____________
Like poles _____________
ATTRACT
REPEL N S N S N S

22. U3e-L8
Review Direct Current
If voltage is constantly 1.5 V, what does its graph over time look like?
1.5 V
Voltage (volts)
Time (seconds)

23. Review Alternating Current
U3e-L8
Review Alternating Current
If voltage is alternating 120 V to -120 V, what does its graph over time look like?
+/-120 V
Voltage (volts)
Time (seconds)

24. Review Electrical Technology
U3e-L1
Review Electrical Technology
Electricity can be used in a thousand different ways. For example:
Electric motors turn electricity into motion.
Light bulbs, fluorescent lamps and LEDs turn electricity into light.
Computers turn electricity into information.
Telephones turn electricity into communication.
TVs turn electricity into moving pictures.
Speakers turn electricity into sound waves.
Stun guns turn electricity into pain.
Toasters, hair dryers and space heaters turn electricity into heat.
Radios turn electricity into electromagnetic waves that can travel millions of miles.
X-ray machines turn electricity into X-rays.

25. An electric motor converts _________ energy into __________ energy.
U3e-L6
Review March 2, 2010
DRILL
An electric motor converts _________ energy into __________ energy.
List 4 household objects that use electric motors.
ELECTRICAL
MECHANICAL
Fans Pumps Garbage disposer
Refrigerators Printers Microwave trays
Washing machines DVD players
Vacuums VCRs
ALMOST EVERY MECHANICAL MOVEMENT IN YOUR HOUSE

26. U3e-L6

27. U3e-L6

28. Complete problem #5 on your worksheet
U3e-L2
Review Problems – Joule’s Law
Complete problem #5 on your worksheet

29. Review Problems – Joule’s Law
U3e-L2
Review Problems – Joule’s Law
A Lexus RX 100h hybrid has a 144 Volt battery system in its trunk. The electric motor that the batteries power can generate 20,000 Watts of power. Sketch a schematic diagram of this circuit. What is the current traveling through this high voltage circuit?
Write the given information:
V = 144 volts
P = 20,000 watts
I = ?
A schematic is a diagram that represents the elements of a system without using realistic pictures

30. ReviewProblems – Joule’s Law
U3e-L2
ReviewProblems – Joule’s Law
Write the given information:
V = 144 Volts
P = 20,000 Watts I = ?
Sketch a schematic diagram of the circuit:
Start with power source
Add conductors
Add load
Add current +
P = 20,000 W
V = 144V -
I = ?

31. Review Problems – Joule’s Law
U3e-L2
Review Problems – Joule’s Law
Write the given
information:
V = 144 Volts
P = 20,000 Watts I = ?
Rearrange, Substitute, and Solve
Sketch a schematic diagram of the circuit:
V = 5V
I = .7A - +
R = ?
P = V x I
I = 20,000W / 144V
R = A
I = P / V

32. STUDY FOR TEST TOMORROW HAND IN REVIEW BEFORE TEST
U3e-L2
HOMEWORK
STUDY FOR TEST TOMORROW
HAND IN REVIEW BEFORE TEST