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Electricity
Lets Review
Atoms have 3 subatomic
  particles                  Charged Atom (atom with a
       Protons = positive    positive or negative charge)
       Electrons = negative    Object must gain or lose
                                 electrons
       Neutrons = neutral      ONLY THE ELECTRONS
                                   MOVE
Neutral Atom                      Measured in Coulombs
   Normal state
   # Protons = # Electrons
Charge & Force
Attraction
                                         Opposites
  Forces pull together         + -
                                          Attract


Repulsion
  Forces push apart        +         +


Rules of Charge
  Like charges repel (+/+ or -/-)
  Opposite charges attract (+/-)
Electricity
Definition: Electricity is the energy associated with
  charged particles as they move from place to place

The type of material determines how charges move
  through them

  Conductors
      Materials that allow electric charges to move easily
      Metals

   Insulators
       Materials that do NOT allow electrons to flow freely
       Rubber, plastic
Forms of Electricity
Static
     Due to build up of charges in or on an
      object


Current
     The flow of electrons in a circuit
Static Electricity
 Static electricity is electricity AT REST
 Occurs between 2 objects that become
  oppositely charged
 Objects involved have unequal electric
  charges
 Examples
   Clothes sticking together in the dryer (if no
    dryer sheet is used)
   Hair standing up after being brushed (on days
    with low humidity)
Lightning
 Large discharge of static electricity
  (electrons transferred from a cloud to the
  Earth)
   Friction from movement of water drops in a
    cloud build up positive and negative charges
   Bolts can deliver 100 million volts
 Safest place to be in a lightning storm is
  inside
 Lightning rods are grounded to Earth to
  distribute the charge
Electric Circuit
An electric circuit is a path for the
 electrons to flow
   Flowing Electrons = current


Electricity can only flow through a CLOSED
  circuit (not an open one)

                    Hi-Lite
                     This!
Voltage (Potential Difference)
 The PUSH that makes electrons flow
  (electrons have potential to flow but wont
  on their own)
 A difference between energy levels is
  needed for flow
   Electrons flow in a circuit when there is an energy
    difference from one end of the energy source to
    the other end of the energy source (like a battery)
 Units = VOLTS (V)
 Symbol = V (capital)
 Measured with a Voltmeter
Electric Current
   The FLOW of electric charges in a circuit
   Units = Amperes (amps)
   Symbol = I
   Speed of Current is affected by
     Type, length, & thickness of wire
     Voltage
     When Voltage , Current
2 Types of Electric Current
Direct Current (DC)
   Electron flow is always in the same direction
   Ex: Batteries


Alternating Current (AC)
   Electrons reverse the direction of flow 60
    times per second
   Ex: Electricity in the Home
Resistance
 Opposition to the flow of electrons
 Unit = Ohm (立)
 Symbol = R

   Highest resistance in:
     Poor conductors
     Thin wires
     Long wires
Ohms Law
Relates Electric Current, Voltage, & Resistance


                V=IxR


   Voltage        Current       Resistance
  (volts, V)      (amps)         (ohms, 立)
Ohms Law Example
Calculate the voltage across a 3立 resistor if
 a 0.5 amp current is flowing through it.


                V=IxR
Ohms Law Example
Calculate the voltage across a 3立 resistor if
 a 0.5 amp current is flowing through it.


                V=IxR
 V=?
 R=3立
 I = 0.5 amp
Ohms Law Example
Calculate the voltage across a 3立 resistor if
 a 0.5 amp current is flowing through it.


                V=IxR
 V=?                V = (0.5 amp)*(3 立 )
 R=3立
 I = 0.5 amp
Ohms Law Example
Calculate the voltage across a 3立 resistor if
 a 0.5 amp current is flowing through it.


                V=IxR
 V=?                V = (0.5 amp)*(3 立 )
 R=3立
 I = 0.5 amp         V = 1.5 v
Ohms Law Example 2
A radio with a resistance of 240 立 is
  plugged into a 120 v outlet. What is the
  current flowing through the outlet?


                V=IxR
Ohms Law Example 2
A radio with a resistance of 240 立 is
  plugged into a 120 v outlet. What is the
  current flowing through the outlet?


                V=IxR
V = 120 v
I=?
R = 240 立
Ohms Law Example 2
A radio with a resistance of 240 立 is
  plugged into a 120 v outlet. What is the
  current flowing through the outlet?


                V=IxR
V = 120 v     120 v = I * 240 立
I=?
R = 240 立
Ohms Law Example 2
A radio with a resistance of 240 立 is
  plugged into a 120 v outlet. What is the
  current flowing through the outlet?


                V=IxR
V = 120 v     120 v = I * 240 立
I=?
R = 240 立      I = 120v / 240 立
Ohms Law Example 2
A radio with a resistance of 240 立 is
  plugged into a 120 v outlet. What is the
  current flowing through the outlet?


                V=IxR
V = 120 v     120 v = I * 240 立
I=?                               I = 0.5 amp
R = 240 立      I = 120v / 240 立
Power
 RATE at which energy is flowing
 The measure of the RATE at which
  electricity does work or provides energy
 Symbol = P
 Units = Watts (W)



                P=IxV
Power Example
If a CD player uses 4.5v with 0.2 amp
 current, how much power does it use?


            P=IxV
Power Example
   If a CD player uses 4.5v with 0.2 amp
    current, how much power does it use?


               P=IxV
P= ?
I = 0.2 amp
V= 4.5 v
Power Example
   If a CD player uses 4.5v with 0.2 amp
    current, how much power does it use?


               P=IxV
P= ?            P=I*V
I = 0.2 amp
V= 4.5 v
Power Example
   If a CD player uses 4.5v with 0.2 amp
    current, how much power does it use?


               P=IxV
P= ?            P=I*V
I = 0.2 amp     P = (0.2amp)(4.5v)
V= 4.5 v
Power Example
   If a CD player uses 4.5v with 0.2 amp
    current, how much power does it use?


               P=IxV
P= ?            P=I*V
I = 0.2 amp     P = (0.2amp)(4.5v)
V= 4.5 v        P = 0.9 W
ELECTRICAL Energy
 Home use of electric energy is based on
  the AMOUNT OF ELECTRICAL POWER
  used per hour
 Measured in kilowatt hours (1000 Watts
  per hour) = kWh


               E=Pxt
Electrical Energy Example
You use your hairdryer for 20 minutes
everyday. The hairdryer uses 1000 kW.
  How many kilowatt-hours does your
       hairdryer use in 6 days?

t = 20min/day*6days = 120min = 2hr

           E = 1000 kW*2Hr
           E = 2000 kWh
Circuits
 Closed loop made up of at least two
  electrical elements
 Consists of at least a power source, wire,
  and a device that uses electrical energy
  (like a light bulb)
Symbols for Circuit Diagrams
                               Positive Side of
 Wire
                               Power Source

 Power Source
                           Negative Side of
 Bulb                     Power Source

 Resistance

 Switch (open)     (closed)
Open Circuit
 Light will not go on because the wire IS
  NOT CONNECTED to the battery on both
  sides; current will NOT flow
Closed Circuit
 Light bulb turns on because the electrical
  current CAN now flow through the
  complete circuit
Series Circuit
 All parts of the circuit are connected one after
  another in a loop
 There is only one path for the electrons to
  follow
 If one part goes out
   The circuit goes from closed to open
   Electricity will not flow
   All parts go out
 The voltage is split through each part of the
  circuit
 The current is the same throughout the circuit
 Example: Christmas Tree Lights
Series Circuit Examples




 A complete circuit turns the
      light bulbs on
Series Circuit Examples
                                 This Light
                                 Bulb is
                                 Burnt Out




   The burnt bulb stops the
  electron flow to the rest of
          the circuit
Parallel Circuit
 There is more than one path or branch for
  the electrons
 If a break occurs in one branch, the
  electrons can still flow in the other
 The voltage is the same throughout each
  branch
 The current is split through each branch
 Example: Household Wiring
Parallel Circuit Examples


                      A        B



          PATH #1


            PATH #2
     Current divides and has
      more than one path
Parallel Circuit Examples
                                      This
                                      Light
                                      Bulb is
                      A               Burnt
                                      Out
                                  B

  Even though Bulb B is burnt
    out, the current still goes
  through the other circuit and
      Bulb A remains lit

More Related Content

Electricity

  • 2. Lets Review Atoms have 3 subatomic particles Charged Atom (atom with a Protons = positive positive or negative charge) Electrons = negative Object must gain or lose electrons Neutrons = neutral ONLY THE ELECTRONS MOVE Neutral Atom Measured in Coulombs Normal state # Protons = # Electrons
  • 3. Charge & Force Attraction Opposites Forces pull together + - Attract Repulsion Forces push apart + + Rules of Charge Like charges repel (+/+ or -/-) Opposite charges attract (+/-)
  • 4. Electricity Definition: Electricity is the energy associated with charged particles as they move from place to place The type of material determines how charges move through them Conductors Materials that allow electric charges to move easily Metals Insulators Materials that do NOT allow electrons to flow freely Rubber, plastic
  • 5. Forms of Electricity Static Due to build up of charges in or on an object Current The flow of electrons in a circuit
  • 6. Static Electricity Static electricity is electricity AT REST Occurs between 2 objects that become oppositely charged Objects involved have unequal electric charges Examples Clothes sticking together in the dryer (if no dryer sheet is used) Hair standing up after being brushed (on days with low humidity)
  • 7. Lightning Large discharge of static electricity (electrons transferred from a cloud to the Earth) Friction from movement of water drops in a cloud build up positive and negative charges Bolts can deliver 100 million volts Safest place to be in a lightning storm is inside Lightning rods are grounded to Earth to distribute the charge
  • 8. Electric Circuit An electric circuit is a path for the electrons to flow Flowing Electrons = current Electricity can only flow through a CLOSED circuit (not an open one) Hi-Lite This!
  • 9. Voltage (Potential Difference) The PUSH that makes electrons flow (electrons have potential to flow but wont on their own) A difference between energy levels is needed for flow Electrons flow in a circuit when there is an energy difference from one end of the energy source to the other end of the energy source (like a battery) Units = VOLTS (V) Symbol = V (capital) Measured with a Voltmeter
  • 10. Electric Current The FLOW of electric charges in a circuit Units = Amperes (amps) Symbol = I Speed of Current is affected by Type, length, & thickness of wire Voltage When Voltage , Current
  • 11. 2 Types of Electric Current Direct Current (DC) Electron flow is always in the same direction Ex: Batteries Alternating Current (AC) Electrons reverse the direction of flow 60 times per second Ex: Electricity in the Home
  • 12. Resistance Opposition to the flow of electrons Unit = Ohm (立) Symbol = R Highest resistance in: Poor conductors Thin wires Long wires
  • 13. Ohms Law Relates Electric Current, Voltage, & Resistance V=IxR Voltage Current Resistance (volts, V) (amps) (ohms, 立)
  • 14. Ohms Law Example Calculate the voltage across a 3立 resistor if a 0.5 amp current is flowing through it. V=IxR
  • 15. Ohms Law Example Calculate the voltage across a 3立 resistor if a 0.5 amp current is flowing through it. V=IxR V=? R=3立 I = 0.5 amp
  • 16. Ohms Law Example Calculate the voltage across a 3立 resistor if a 0.5 amp current is flowing through it. V=IxR V=? V = (0.5 amp)*(3 立 ) R=3立 I = 0.5 amp
  • 17. Ohms Law Example Calculate the voltage across a 3立 resistor if a 0.5 amp current is flowing through it. V=IxR V=? V = (0.5 amp)*(3 立 ) R=3立 I = 0.5 amp V = 1.5 v
  • 18. Ohms Law Example 2 A radio with a resistance of 240 立 is plugged into a 120 v outlet. What is the current flowing through the outlet? V=IxR
  • 19. Ohms Law Example 2 A radio with a resistance of 240 立 is plugged into a 120 v outlet. What is the current flowing through the outlet? V=IxR V = 120 v I=? R = 240 立
  • 20. Ohms Law Example 2 A radio with a resistance of 240 立 is plugged into a 120 v outlet. What is the current flowing through the outlet? V=IxR V = 120 v 120 v = I * 240 立 I=? R = 240 立
  • 21. Ohms Law Example 2 A radio with a resistance of 240 立 is plugged into a 120 v outlet. What is the current flowing through the outlet? V=IxR V = 120 v 120 v = I * 240 立 I=? R = 240 立 I = 120v / 240 立
  • 22. Ohms Law Example 2 A radio with a resistance of 240 立 is plugged into a 120 v outlet. What is the current flowing through the outlet? V=IxR V = 120 v 120 v = I * 240 立 I=? I = 0.5 amp R = 240 立 I = 120v / 240 立
  • 23. Power RATE at which energy is flowing The measure of the RATE at which electricity does work or provides energy Symbol = P Units = Watts (W) P=IxV
  • 24. Power Example If a CD player uses 4.5v with 0.2 amp current, how much power does it use? P=IxV
  • 25. Power Example If a CD player uses 4.5v with 0.2 amp current, how much power does it use? P=IxV P= ? I = 0.2 amp V= 4.5 v
  • 26. Power Example If a CD player uses 4.5v with 0.2 amp current, how much power does it use? P=IxV P= ? P=I*V I = 0.2 amp V= 4.5 v
  • 27. Power Example If a CD player uses 4.5v with 0.2 amp current, how much power does it use? P=IxV P= ? P=I*V I = 0.2 amp P = (0.2amp)(4.5v) V= 4.5 v
  • 28. Power Example If a CD player uses 4.5v with 0.2 amp current, how much power does it use? P=IxV P= ? P=I*V I = 0.2 amp P = (0.2amp)(4.5v) V= 4.5 v P = 0.9 W
  • 29. ELECTRICAL Energy Home use of electric energy is based on the AMOUNT OF ELECTRICAL POWER used per hour Measured in kilowatt hours (1000 Watts per hour) = kWh E=Pxt
  • 30. Electrical Energy Example You use your hairdryer for 20 minutes everyday. The hairdryer uses 1000 kW. How many kilowatt-hours does your hairdryer use in 6 days? t = 20min/day*6days = 120min = 2hr E = 1000 kW*2Hr E = 2000 kWh
  • 31. Circuits Closed loop made up of at least two electrical elements Consists of at least a power source, wire, and a device that uses electrical energy (like a light bulb)
  • 32. Symbols for Circuit Diagrams Positive Side of Wire Power Source Power Source Negative Side of Bulb Power Source Resistance Switch (open) (closed)
  • 33. Open Circuit Light will not go on because the wire IS NOT CONNECTED to the battery on both sides; current will NOT flow
  • 34. Closed Circuit Light bulb turns on because the electrical current CAN now flow through the complete circuit
  • 35. Series Circuit All parts of the circuit are connected one after another in a loop There is only one path for the electrons to follow If one part goes out The circuit goes from closed to open Electricity will not flow All parts go out The voltage is split through each part of the circuit The current is the same throughout the circuit Example: Christmas Tree Lights
  • 36. Series Circuit Examples A complete circuit turns the light bulbs on
  • 37. Series Circuit Examples This Light Bulb is Burnt Out The burnt bulb stops the electron flow to the rest of the circuit
  • 38. Parallel Circuit There is more than one path or branch for the electrons If a break occurs in one branch, the electrons can still flow in the other The voltage is the same throughout each branch The current is split through each branch Example: Household Wiring
  • 39. Parallel Circuit Examples A B PATH #1 PATH #2 Current divides and has more than one path
  • 40. Parallel Circuit Examples This Light Bulb is A Burnt Out B Even though Bulb B is burnt out, the current still goes through the other circuit and Bulb A remains lit