1. Electric Charge and Static Electricity

2. Like charges attract, opposite charges repel
True
False
Statement
Like charges attract, opposite charges repel
Electric charge is due to an excess or shortage of electrons
Law of Conservation of Charge says that charge is constant
You can charge an object by touching, friction and induction
The SI unit for static electricity is the coulomb

3. Electric Charge
Property that causes subatomic particles (_____, ______) to attract/repel each other
2 Types
Positive- Protons
Negative- Electrons
Net Electric Charge
Excess or shortage of electrons
SI Unit
Coulomb (C)
6.24 x 1018 electrons

4. Electric Forces Like charges Opposite charges Electric Force
Repel
Opposite charges
Attract
Electric Force
Forces of attraction and repulsion between electrically charged objects
Charles Coulomb
Discovered electric forces are similar to the law of Gravitation

5. Electric Fields The strength of an electric field depends on
The amount of charge that produces the field
The distance from the charge
The force depends on
The net charge in the object
The strength and direction of the fields position

6. Static Electricity and Charging
The study of the behavior of electric charges and how charge is transferred
Law of Conservation of Charge
Total charge in an isolated system is constant
1. Charging by Friction
Ex. Rubbing a Balloon in your hair
Electrons move due to attraction

7. Static Electricity and Charging
2. Charging by Contact
Ex. Van de Graaff generator
3. Charging by Induction
Ex. Reaching for a doorknob after rubbing feet across carpet
Induction- transfer of charge without contact between materials

8. Static Discharge
Occurs when a pathway through which charges can move forms suddenly

9. Electric Current and Ohm’s Law
Ch 20.2

10. DC current is current in all direction, while AC current reverses
True
False
Statement
DC current is current in all direction, while AC current reverses
Thickness, length and temperature affect resistance
Ohm’s Law says resistance(R), voltage(V) and current(I) are co-related
Potential difference is also voltage, or the difference between 2 places in an electric field
Conductors help current to flow easily while insulators prevent current from flowing

11. Electric Current Continuous path through which charge can flow SI Unit
Ampere/Amp (A)
1 C/s
2 Types of Current
1. Direct Current (DC)
Charge flows in 1 direction
Flashlights, battery operated machines
2. Alternating Current (AC)
Charge flow reverses direction
Electricity in buildings

13. Conductors and Insulators
Electric Conductor
Electric Insulator
Material electric charge can flow easily through
Cu, Ag
Material electric charge cannot flow easily through
Wood, plastic, rubber, air

14. Resistance Opposition to the flow of charges in a material SI Unit
Ohm
Superconductor
Material that has almost zero resistance when it is cooled to a low temperature
3 Factors Affecting Resistance
Thickness
Length
Temperature

15. Voltage
In order for a charge to flow in a conducting wire, the wire must be connected in a complete loop that includes a source of electric energy

16. Voltage Battery Solar cells, generators
Potential Difference
Voltage Sources
Charges flow from higher to lower potential energy
PD- difference in electrical PE between 2 places in an electric field
SI Unit
J/C or Volts
Also called voltage
Battery
Device that converts chemical energy to electrical energy
Solar cells, generators

17. Ohm’s Law
Voltage(V) in a circuit equals the product of the current(I) and the resistance(R)
Increasing the voltage increases current
Keeping the same voltage and increasing resistance decreases the current
V = I x R
Ex. 3 amps x 3 ohms= 9volts

18. Electric Circuits
Ch 20.3

19. Circuit diagrams use symbols to represent an electrical circuit
True
False
Statement
Circuit diagrams use symbols to represent an electrical circuit
A closed circuit stops, while an open circuit is free to flow
Series circuits only have one way to flow
Parallel circuits have 2 or more paths in which to flow
A fuse prevents current overload, and melts in over use

20. Circuit Diagrams Electric Circuit Circuit Diagrams Open Circuit
Complete path through which charge can flow
Circuit Diagrams
Use symbols to represent parts of a circuit, electrical energy and devices run by electrical energy
Open Circuit
Open switch = current stops
Closed Circuit
Closed switch = complete flow of current

21. Series Circuit Charge has only 1 path through which it can flow
If 1 element stops working, none of the elements can operate

22. Parallel Circuit
Electric circuit with 2 or more paths through which charges can flow
If 1 element stops functioning the rest can still operate

23. Power and Energy Calculations
Electrical Power
Rate at which electrical energy is converted to another form of energy
SI Unit
J/s or Watt (W)
Kilowatt (kW)
P(watts)= I(amps) x V(volts)
Electrical Energy
SI Unit
W s
kW hr
E= P x t

24. Math Practice pg 611 1. 3. 2.

25. Electrical Safety Electrical Energy Safety Correct wiring Fuses
Circuit Breakers
Insulation
Grounded Plugs

26. Electrical Safety Fuse Circuit Breaker Grounding Home Safety
Personal Safety
Fuse
Prevents current overload
Blowing a fuse- melting a fuse
Circuit Breaker
Switch the opens when a current in a circuit is too high
Grounding
Transfer of excess charge through a conductor to Earth

27. Electronic Devices
Ch 20.4

28. Analog signals change voltage, while digital signals change current.
True
False
Statement
Analog signals change voltage, while digital signals change current.
Vacuums are the best way to control electronic signals, compared to solid state components
A diode has a n-type and p-type semiconductor
A n-type semiconductor flows protons, while a p-type semiconductor flows electrons
An integrated circuit replaces many vacuums and is also called a microchip

29. Electronic Signals Electronics Electronic Signal
The science of using electronic current to process/transmit information
Electronic Signal
Information sent as patterns in the controlled flow of electrons through a circuit

30. Electronic Signals
Analog Signal
Digital Signals
Smoothly varying signal produced by continually changing the voltage or current
AM radio
Encodes information as a string of 1s and 0s
DVDs

31. Vacuum Tubes Change alternating current into direct current
Increase the strength of a signal
Turn a current on or off
Cathode Ray Tube
Used in computer monitors, TVs
Phosphors glow red, green or blue

32. Semiconductors
Crystalline solid that conducts current only under certain conditions
N Type Semiconductor
Current is a flow of electrons
Made by adding P to Si
P Type Semiconductor
Appears as though positive charge flows
Made by adding B to Si

33. Solid State Components
Used solids instead of vacuums to control current
1. Diodes
Solid state component that combines N Type and P Type semiconductors
Flows from N to P
Can change alternating current to direct

34. Solid State Components
2. Transistors
Solid state component with 3 layers of semiconductors
Used as a switch or amplifier
3. Integrated Circuits
Thin slice of Si containing many solid state components
Chips or microchips
Perform as well as a network of vacuums

35. Communications Technology
Computer
Programmable device that stores and processes information
Communication devices use microchips to make them
Portable
Reliable
affordable