1. ELECTRICITY Content Statements:
1. Energy can be transformed or transferred but it is never lost.
2. Energy can be transferred through a variety of ways.

2. ELECTRICITY
Big Idea:
Electricity is all around us, but do you know what electricity is?
Electricity is the interaction of electric charges. An electric charge is a physical property of protons and electrons, particles that make up every atom. When charges from one piece of matter interact with those from another piece of matter, they produce electric forces.
Electrical energy can transform into other types of energy and transfer from one location to another.

3. ELECTRIC CHARGE AND STATIC ELECTRICITY (p. 4)
Atoms and Charge (p. 4)
All matter is composed of very small particles called atoms.
Atoms are made of even smaller particles called protons, neutrons, and electrons.
Protons and electrons are charged particles and neutrons are not.

4. ELECTRIC CHARGE AND STATIC ELECTRICITY
Charges Can Exert Forces (p. 5)
A charged object exerts a force – a push or a pull – on other charged objects.
There are two types of charge – positive and negative.
The force between two charged objects varies depending on whether the objects have the same type of charge or opposite charges.

5. ELECTRIC CHARGE AND STATIC ELECTRICITY
The law of electric charges states that like charges repel and opposite charges attract.

6. An electric force is the force between charged objects.
ELECTRIC CHARGE AND STATIC ELECTRICITY
The Electric Force and the Electric Field (p. 5)
An electric force is the force between charged objects.
The strength of the force is determined by two factors.
One factor is the size of the charges (the greater the charges are, the greater the electric force).
The other factor is the distance between the forces (the closer together the charges are, the greater the electric force).

7. ELECTRIC CHARGE AND STATIC ELECTRICITY
One factor is the size of the charges (the greater the charges are, the greater the electric force).
The other factor is the distance between the forces (the closer together the charges are, the greater the electric force).
weaker 1+ 1- 3+
stronger 3-
weaker
stronger

8. ELECTRIC CHARGE AND STATIC ELECTRICITY
The Electric Force and the Electric Field (p. 5)
An electric field is a region around a charged particle that can exert a force on another charged particle (attract or repel).
*Think personal space “bubble”.
Out of the field
Her hair is attracted to the comb and is within the electric field of the comb. If the comb moves farther away, it will no longer exert a force over her hair.
In the field
In the field
Out of the field

9. ELECTRIC CHARGE AND STATIC ELECTRICITY
This sock is positively charged because some of its atoms lost electrons.
Charge It! (pgs. 6-8)
Although an atom contains charged particles, the atom itself does not have a charge.
Objects become charged because the atoms in the objects can gain or lose electrons.
If the atoms of an object lose electrons, the object becomes positively charged. If the atoms of an object gain electrons, the object becomes negatively charged.
This sock is negatively charged because some of its atoms gained electrons.
Objects do NOT gain and lose protons… only ELECTRONS. This is because electrons are located in the atom’s electron cloud (outside of the nucleus) and so they can easily rub off onto other objects.

10. No charges were created or destroyed.
ELECTRIC CHARGE AND STATIC ELECTRICITY
Charge It! (pgs. 6-8)
Conservation of Charge: When you charge objects by any method, no charges are created or destroyed; electrons simply move from one atom to another.
Both object A and object B are neutral before contact.
No charges were created or destroyed.

11. ELECTRIC CHARGE AND STATIC ELECTRICITY
Charge It! (pgs. 6-8)
Electroscope: a device used to determine if an object has a charge.
The two metal pieces will be in a neutral position (not pushing or pulling) if the object does not have a charge.
The two metal pieces will pull apart if the object has a charge (positive or negative).
You simply take the object and touch the top of the electroscope with it.

12. ELECTRIC CHARGE AND STATIC ELECTRICITY
Moving Charges (pgs. 8-9) 
Conductor: a material in which charges can move freely. Most metals are good conductors because some of the electrons in the metals are free to move about.
Insulator: a material in which charges cannot easily move. Insulators do not conduct charges very well because electrons are tightly bound and cannot flow freely.

13. Conductors Insulators
ELECTRIC CHARGE AND STATIC ELECTRICITY
Conductors
Insulators

14. ELECTRIC CHARGE AND STATIC ELECTRICITY
Static Electricity: the buildup of electric charges on an object.
Have you ever walked across a room and then got zapped on a door handle?
B. The hand touches the metal doorknob resulting in a rapid transfer of electrons. A shock is felt.
A. The hand is negatively charged (a surplus of electrons).

15. CHARGE REVIEW

16. What are the tiny particles that make up all matter?
Electricity
Atoms
Electrons
Charges

17. What type of charge do protons have?
Positive Charge
Opposite Charge
Negative Charge
No Charge

18. An object becomes charged when atoms gain or lose ___.
Protons
Neutrons
Electrons
Protons and Electrons

19. If two charges repel each other, the two charges must be
Positive and Positive
Positive and Negative
Negative and Negative
Positive and Positive OR Negative and Negative

20. Which of the following laws says that opposite charges attract?
the law of electric charges
the law of atomic charges
the law of charged atoms
the law of electrons

21. What do we call the region around a charged particle?
electric charge
electric force
electric field
atomic field

22. Determine the overall charge of these socks. Will they stick together?
YES NO

23. Determine the overall charge of these socks. Will they stick together?
YES NO

24. ELECTRIC CURRENT (p. 15)
Electrical energy can be generated by a variety of methods. A battery produces electrical energy effectively, but electric power plants provide most of the electrical energy used every day.

25. Electric current is a continuous flow of charge.
ELECTRIC CURRENT (p. 15)
Current Revisited (p. 15)
Electric current is a continuous flow of charge.
Current: the rate at which charge passes a given point (measured with an ammeter)
The higher the current is, the more charge passes the point each second.
Ampere (A): the unit for current; sometimes called amp for short
ammeter

26. When you flip a light switch, the light comes on instantly.
Charge Ahead! (p. 15)
When you flip a light switch, the light comes on instantly.
Flipping the light switch sets up an electric field in the wire that connects to the light bulb. The electric field causes the free electrons in the wire to move. The electrons start moving through the wire at practically the same instant.
ELECTRIC CURRENT (p. 15)

27. HINT: Watch the arrows representing current direction
ELECTRIC CURRENT
Let’s See, AC/DC… (p. 16)
There are two types of electric current – direct current (DC) and alternating current (AC).
Direct Current: the charges always flow in the same direction
Alternating Current: the charges continually switch from one direction to the reverse direction
DIRECT CURRENT
HINT: Watch the arrows representing current direction
ALTERNATING CURRENT

28. ELECTRIC CURRENT
Let’s See, AC/DC… (p. 16)
The electric current in batteries and cells is DC, but the electric current from outlets in your home is AC.
Even though you can’t see the arrows in a wire, you can determine the type of current a circuit has by looking at where the current is coming from.

29. DC AC
DC or AC?

30. The current in a wire is determined by voltage.
ELECTRIC CURRENT
Voltage (pgs )
The current in a wire is determined by voltage.
Voltage: the difference in energy per unit charge as a charge moves between two points in the path of a current
Voltage is another word for potential difference.
Point
Point

31. Voltage is expressed in volts (V).
ELECTRIC CURRENT
Voltage (pgs )
Voltage is expressed in volts (V).
The higher the voltage is, the more energy is released per charge (the greater the charge).
Most electrical outlets provide a voltage of 120V.
Voltmeter

32. Resistance also determines the current in wire.
ELECTRIC CURRENT
Resistance (pgs )
Resistance also determines the current in wire.
Resistance: the opposition to the flow of electric charge.
Resistance is measured in ohms (W).
Think of resistance as “electrical friction.”
Voltage is the push that forces the electrons to flow (current).
Resistance opposes the current, slowing down the electrons.

33. The higher the resistance of a material is, the lower the current is.
ELECTRIC CURRENT
Wires can vary from one to another – different material, thickness, length, and even temperature. All of these characteristics affect resistance (or how much the electrons are slowed.
Resistance (pgs )
The higher the resistance of a material is, the lower the current is.
Resistance varies depending on the object’s material, thickness, length, and temperature.

34. Material
Good conductors have low resistance. Resistance of insulators is so high that electric charges cannot flow through them.
Materials with low resistance are used to make wires.
Tungsten light bulbs have a high resistance which causes electrical energy to be converted to light and thermal energy.
ELECTRIC CURRENT

35. ELECTRIC CURRENT Thickness and Length
Thick wires have less resistance than thin wires because thick wires have more spaces for charges to flow. Long wires have more resistance than short wires because long wires require charges to move around more.
Thickness decreases, so resistance increases.
short wire
long wire
Length increases, so resistance increases.

36. ELECTRIC CURRENT Temperature
In general, the resistance of metals increases as temperature increases.
Atoms move faster at higher temperatures and get in the way of flowing electric charges.
Imagine a flame warming up the atoms of a metal wire. As the wire gets warmer, its atoms will move faster. Now imagine the free electrons trying to pass through. The higher the temperature, the more resistance there is.

37. Thin wires have MORE resistance than thick wires.
Think of a traffic jam. Have you ever seen four lanes of highway go down to two lanes (i.e. for construction)? The cars slow down. Same idea applies to electrons trying to move in a thin wire.

38. Slice View of Wires
Which wire would have more resistance? Which one would make it more difficult for electrons to pass through?
Wire 1
Wire 2
Low resistance
High resistance
The thinner the wire has less space for the electrons to travel. This means that wire 2 has more resistance than wire 1.

39. Long wires have MORE resistance than short wires.
The longer a wire is, the longer the electrons have to travel (and the more likely they will collide and slow down) which increases resistance.
Long wires have MORE resistance than short wires.

40. Low resistance
Wire 1
High resistance
Wire 2
Which wire would have more resistance? Which one would make it more difficult for electrons to pass through?
The longer the wire is, the more distance/length there is for the electrons to travel. This means that wire 2 has more resistance than wire 1.

41. Conductors have LESS resistance than insulators.

42. Warmer objects have MORE resistance than cooler objects.
When a wire warms up, its atoms move faster. This makes collisions between the electrons and atoms more likely than when the wire is cooler. Resistance increases with temperature.
Bumper cars, anyone?
Warmer objects have MORE resistance than cooler objects.

43. Name that TERM!
______ 1. the rate at which charge passes a given point
A. Voltage
______ 2. the opposition to the flow of electric charge
B. Resistance
______ 3. the difference in energy per unit charge as a
charge moves between two points in the
path of a current
C. Temperature
D. Current D. B. A.

44. Name that TERM!
______ 1. the region around a charged particle
A. Electric Field
______ 2. the tiny particles that make up all matter
B. Resistance
______ 3. the force between charged objects
C. Atoms
D. Electric Force A. C. D.

45. Charge! C. A. D. ______ 1. the charge an electron has Electron(s)
______ 2. an atom gains or loses __________ to become
charged
Neutral
______ 3. positively charged subatomic particle
C. Negative
D. Proton(s) C. A. D.

46. Name that TOOL! ______ 1. tool used to measure current B.
A. Electroscope
______ 2. tool used to measure voltage
B. Ammeter
______ 3. tool used to measure whether or not an
object has a charge
C. Voltmeter
D. Currentmeter B. C. A.

47. Attract or repel? A B
Attract
Repel

48. Name that UNIT! ______ 1. unit used to measure voltage A.
A. Volts
______ 2. unit used to measure current
B. Watts
______ 3. unit used to measure resistance
C. Ohms
D. Amperes A. D. C.

49. Which has more resistance? Which has less resistance?
THIS or THAT? A B
Which has more resistance?
Thick wire
Thin wire
Short wire
Long wire
Which has less resistance?
Conductor
Insulator
Warmer objects
Cooler objects

50. A circuit always begins and ends in the same place forming a loop.
ELECTRIC CIRCUITS (p. 22)
A circuit always begins and ends in the same place forming a loop.
Circuit: a complete, closed path through which electric charges flow.
This circuit is CLOSED or COMPLETE because there are no breaks.
This circuit is OPEN or INCOMPLETE because there is a break.

51. Load: a device that uses electrical energy to do work.
ELECTRIC CIRCUITS (p. 22)
Parts of a Circuit (p. 22)
All circuits consist of an energy source, a load, and wires to connect the other parts together.
Load: a device that uses electrical energy to do work.
Wire
(Lead)
Wire
(Lead)
Energy Source
Load
Load
Load

52. ELECTRIC CIRCUITS (p. 22)
The energy source can be a battery, a photocell, a thermocouple, or an electric generator at a power plant.
Wires connect the other parts of a circuit together and are made of conducting materials with low resistance, such as copper.
Examples of loads are light bulbs, appliances, televisions, and motors.
BATTERY
THERMOCOUPLE
PHOTOCELL
ELECTRIC GENERATOR

53. Opening and Closing a Circuit (p. 23)
ELECTRIC CIRCUITS
Opening and Closing a Circuit (p. 23)
Sometimes a circuit contains a switch.
Switch: used to open and close a circuit; usually made of two pieces of conducting material, one of which can be moved

54. When metal touches metal, the electrons can flow through the switch.
ELECTRIC CIRCUITS
Opening and Closing a Circuit (p. 23)
For charges to flow in a circuit, the switch must be closed, or “turned on.”
If a switch is open, or “off,” the loop is broken and no charges can flow through the circuit.
When metal touches metal, the electrons can flow through the switch.
Side note:
Most diagrams do not come in color. Do not let the color fool you. You have to examine the circuit to determine whether or not it is closed.

55. Should the load be lit in this diagram? Explain why or why not.
Should the load be lit in this diagram? Explain why or why not.
ELECTRIC CIRCUITS
NO! This circuit is open. The electrons cannot pass through the switch; therefore, the load should not be lit.
Uh-oh! Metal is not
touching metal.

56. Name the Parts of This Circuit!
Load
Energy Source
Wire
(Lead)
Switch

57. Types of Circuits (p. 23) ELECTRIC CIRCUITS
Types of Circuits (p. 23)
Look around the room and find objects that use electricity. All of these objects are loads in a large circuit. Most circuits contain more than one load. Loads can be connected in two different ways – in series or in parallel.
ELECTRIC CIRCUITS

58. Series Circuits (p. 24) ELECTRIC CIRCUITS
Series Circuits (p. 24)
Series Circuit: a circuit in which all parts are connected in a single loop
The charges traveling through a series circuit must flow through each part and can only follow one path.
All loads in a series circuit share the same current. All of the light bulbs in a series circuit glow with the same brightness.
ELECTRIC CIRCUITS

59. Series Circuits (p. 24) ELECTRIC CIRCUITS
Series Circuits (p. 24)
If you add more light bulbs, the resistance of the circuit would increase and the current would decrease, therefore all of the bulbs would be dimmer.
Charges pass through one load after another, in order, around the circuit. If one load is broken or missing, the other loads will not work.
ELECTRIC CIRCUITS

60. Parallel Circuits (p. 25) ELECTRIC CIRCUITS
Parallel Circuits (p. 25)
Parallel Circuit: a circuit in which different loads are located on separate branches
Because there are separate branches, the charges travel through more than one path
The loads in a parallel circuit do not have the same current, but each load uses the same voltage.
ELECTRIC CIRCUITS

61. ELECTRIC CIRCUITS Parallel Circuits (p. 25)
Parallel Circuits (p. 25)
You can connect loads that require different currents to the same parallel circuit.
Each branch of the circuit can function by itself. If one load is broken or missing, charges will still run through the other branches. (your home)

62. Name that Circuit! Series or Parallel?
WHY SERIES?
All of the parts of the circuit are connected in one single loop.
The electrons only have ONE path to take.

63. Name that Circuit! Series or Parallel?
WHY PARALLEL?
All of the parts of the circuit are connected in multiple loops.
The electrons have more than one path to take.

64. Name that Circuit! Series or Parallel?
WHY PARALLEL?
All of the parts of the circuit are connected in multiple loops.
The electrons have more than one path to take.

65. Name that Circuit! Series or Parallel?
WHY SERIES?
All of the parts of the circuit are connected in one single loop.
The electrons only have ONE path to take.

66. This or That! Which one has only one path for current to follow?
NOW WATCH THIS!
Which one has only one path for current to follow?
Series
Parallel
Which one has more than one path for current to follow?
Which one has loads functioning on their own (and can work if one load is missing/broken)?
Which one has loads functioning in order (and cannot work if one is missing/broken)?

67. PRODUCING ELECTRICITY
Power Plant
Coal is used to produce about 50% of the world’s electricity. Coal is burned to produce steam which turns a turbine. Mechanical energy from the turbine transforms into electrical energy in the generator.
PRODUCING ELECTRICITY

68. Geothermal
Heat energy (steam) from within EARTH’S surface turns turbines (vent/geyser)

69. Nuclear
Energy that comes from the NUCLEI, or centers of atoms

70. Wind
Moving AIR or wind that turns a turbine

71. Hydroelectric
Moving WATER causes turbines in a dam to turn

72. Solar
Energy from the SUN which is converted using photovoltaic cells

73. Biomass
Matter formed from PLANTS and ANIMALS that contains stored energy