Electricity

1
Electricity

• Chapter 1

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Electric Charge

• Charges Exert Force
• Atoms are composed of particles with ______.
  The law of electric charges states that like
  charges _____and opposite charges _______

3
The Force Between Protons and Electrons

• Protons and electrons have ________ charges, they
  are ________ to each other

4
The Electric Force and the Electric Field

• _____________ the force of attraction or
  repulsion on a charged particle that is due to an
  electric field
•  
• ____________ the space around a charged object
  in which another charged object experiences an
  electric force

5
Charge it!

• Friction

• Conduction

• ________- occurs when electrons are wiped
• from one object to another
•  
•  

• __________ electrons move from one object to
  another by direct contact.
•  

6
Charge it!

• _________ charges in an uncharged metal object
  are rearranged without direct contact with a
  charged object

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Conservation of Charge

• When you charge something by any method,
  ____________________________________. The numbers
  of ________ and _______ stay the same.
• Detecting Charge
• You can use a device called an _____________ to
  see if something is charged

8
Moving Charges

• __________- a material in which charges can move
  easily
• Examples
• __________- a material in which charges
• cannot move freely
• Examples

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Static Electricity

• _________________ electric charge at rest
  produced from friction or induction
• _________________ the release of electricity
  stored in a source

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1.2 Electric Current Energy

• _______________ rate at which charges pass a
  given point
• When you flip a switch, an _____________ is set
  up in the wire at the speed of light. The
  electric field causes the _________ in the wire
  to move.
• This electric field is created so quickly that
  all electrons start moving through the wire
  _________.
• Think of the electric field as a command to the
  electrons to charge ahead.

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Types Electric current

• Direct Current (DC)

• Alternating Current (Ac)

• ___________________ charges always flow in one
  direction.
• Ex

• ___________________ charges shift
• from flowing in one direction to
  flowing in
• the reverse direction
• EX

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Voltage and Energy

• _______ the potential difference between points
• SI unit
•  
• You can think of voltage as the amount of energy
  released as a charge moves between two points in
  the path of a current.
• As long as there is a voltage between _________,
  charges will flow in the wire. The ____ of the
  current depends on the _______

13
Varying Nature of Voltage

• Different devices need different levels of
  voltage.
• 1.5 V 9 V
  12 V

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Resistance

• ___________ opposition to the flow of electric
  charge
• SI unit
• Good conductors, such as copper, have
  _____________
• Poor conductors, such as iron, have
  ______________
• Resistance depends on thickness, length,
  temperature
• Thick, _____ wires have ____ resistance than
  ____, thin wires.
• The resistance of metals _________ as temperature
  _________

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Resistance
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Generating Electrical Energy

• Remember energy is not created or destroyed it
  only changes forms
• Parts of a Cell
• A cell contains a mixture of chemicals called an
  __________. Every cell also has a pair of
  __________made from conducting materials

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Types of Cells

• There are 2 types of cells
• ___ have an electrolyte
• Example batteries sulfuric acid is the
  electrolyte
• ___ have a dry electrolyte
• Example small radios or flashlights

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Generating Electrical Energy

• Cells change chemical or radiant energy into
  electrical energy. Batteries are made of one or
  more cells.
• ____________ can take thermal energy and transfer
  it to electrical energy.
• _________convert light energy into electrical
  energy.

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1.3 Electrical Calculations

• How fast is a nanosecond? A nanosecond (ns) is
  one-billionth of a second. Electrical signals
  travel at 30 cm/ns. Calculate how far electrical
  signals travel in 1 second.
•  

20
Connecting Current, Voltage, and Resistance

• Georg Ohm Ohm (1789 1854) studied the resistance
  of materials. He measured the current that
  resulted from different voltages applied to a
  piece of metal wire.
• Ohms Law the ratio or voltage (V) to current
  (I) is the resistance (R) of a material
• V I x R

Electric Power
Unit SI Unit
Voltage (V) V - volt
Current (I) A- Amps
Resistance (R) Ohm - ?
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Ohms Law Calculations

• Ex 1 What is the voltage if the current is 2 A
  and the resistance is 12 ? ?
• Ex 2 Find the voltage if the current is 0.2 A
  and the resistance is 2 ?

22
Ohms Law Calculations

• Ex 3 The resistance of an object is 4 ?. If the
  current in the object is 9 A, what is the voltage
  used?
• Ex 4 An object has a resistance of 20 ?.
  Calculate the voltage needed to produce a current
  of 0.5 A.

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Electric Power

• Electrical Power (P) the rate at which
  electrical energy is converted into other forms
  of energy
• Si Unit Watts (W)
• Power voltage x current
• P V x I

Unit SI Unit
Voltage (V) V - volt
Current (I) A- Amps
Power (P) W - Watts
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Electrical Power Calculations

• Ex 1 A toaster draws approximately 10 A of
  current. A home receives 120 V at each electrical
  outlet. What is the power of the toaster?
• Ex 2 A car uses a 12 V battery. One headlight
  draws 3.0 A. What is the power of the headlight?

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Electrical Power Calculations

• EX 3 A light bulb draws a 0.5 A current at a
  voltage of 120 V. What is the power rating of the
  light bulb?

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Electrical Energy

• Measuring Household Energy Use
• Different amounts of electrical energy are used
  each day in a home. Electric companies usually
  calculate electrical energy by multiplying the
  power in kilowatts by the time in hours.

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1.4 Electric Circuit

• Just like a roller coaster, an electric circuit
  always forms a loop it _____ and ____ at the
  ____ place
• Parts of an Electric Circuit
• (light bulb, appliance)

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Switches

• Sometimes, a circuit also contains a _____
• _____ opens or closes a circuit
• _____ electrons can ____
• _____ electrons _____________

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Types of Circuits

• ______________ a circuit in which the parts are
  joined one after another such that the current in
  each part is the same.
• _________for charges to follow charges must
  flow through each part of the circuit
• The voltage across each load is _________

Series circuits are useful in wiring burglar
alarms. If any part of the circuit fails, there
will be __________in the system and the alarm
will sound.
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Types of circuits

• _______________- a circuit in which the parts are
  joined in branches so that the voltage (potential
  difference) across each part is the same
• Loads do ___have the _________________
• Charges have more than ___ path to follow

Parallel Circuits are used in almost all
appliances and decorative string lights
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Household circuit safety

• Circuits can ____ if they are __________ or a
  wire breaks or has water damage.
• To prevent fire
• A thin strip of metal in circuit that the charges
  flow through.
• If the current is too high, the metal will
  melt and the circuit
• is broken
• A switch that automatically opens if the current
  is too high. A metal strip heats up, bends, and
  opens the switch stopping the flow of current