Electricity

• Current


  The rate at which charge flows through an object
• Current


  Charge / Time
• Ways electricity can be transferred


  • Conduction
  • Convection
  • Radiation
• Ammeter


  Measures current, must be connected in series with the circuit to measure the current flowing through that part of the circuit
• Voltmeter


  Measures voltage, must be connected in parallel with the component being measured to avoid changing its resistance
• Ammeter measures current, it must be connected in series with the component being measured
• Resistance


  The opposition that a material offers to the flow of electric current
• Voltmeter measures voltage, it must be connected in parallel to the component being measured
• Conduction


  Occurs when particles collide with other charged particles causing them to move
• Metals


  Electrons are free to move around so they carry the electric current
• Insulators


  Have no free electrons so there is no flow of current
• Voltmeter measures potential difference, it must be connected in parallel with the component being measured
• Ohm's law


  The current passing through a resistor is directly proportional to the voltage across the resistor
• Ohm's law states that the potential difference across a resistor is directly proportional to the current passing through it
• Resistance is the opposition to the flow of electric current
• Ohm's law


  Potential difference (volts) equals current times resistance (ohms)
• Resistors


  Used to control the flow of electric current in circuits
• Unit of resistance


  Ohms (Ω)
• Potential difference


  The energy per unit charge needed to move one coulomb from one point to another
• Even if you don't totally understand what electricity is, you are probably very familiar with it and use it throughout your day
• Using electricity


  • Turning on lights in your room when you wake up
  • Using your electric toothbrush to brush your teeth
  • Using your toaster or toasting your bagels for breakfast
  • Turning on your computer and bringing up this video
• Electricity


  Tiny particles that we call electrons
• On their own, the electrons don't do much, but when they move, their movement generates energy
• How electricity works


  1. Electrons flow through a loop, which we call an electric circuit

  2. This can turn up lights, move motors, and heat things up
• Electric circuit


  • A path through which electricity flows
  • Requires a battery to provide the power that causes the electricity to move around the circuit
  • Needs to be closed for it to work, if there is a break anywhere in the circuit, it won't work
• Components in a circuit


  • Wires
  • Lights
  • Switches
• Switches


  Components that purposefully break the circuit, but then allow you to open and close it as needed
• Switch is down


  Circuit is broken, light is off
• Switch is turned on

  Circuit is completed, light turns on
• Static Electricity


  A stationary electrical charge that is built up on the surface of a material
• What Is Static Electricity?

  • Hair standing on end is a common "visual representation of static"
• Electro-negativity ranking of materials

  • Glass
  • Human Hair
  • Nylon
  • Silk
  • Fur
  • Aluminum
  • Paper
  • Cotton
  • Copper
  • Rubber
  • PVC
  • Teflon
• A plexiglass rod rubbed with fur

  Picks up a positive electric charge
• A rubber rod rubbed with fur

  Picks up a negative electric charge
• Charging by friction


  Rubbing materials transfers electrons from one material to the other
• Electrostatics


  The interaction between static electric charges
• Where do charges come from?

  When a balloon rubs a piece of wool, electrons are pulled from the wool to the balloon
• The balloon has more electrons than usual and is negatively charged, the wool is positively charged
• Static Discharge


  The human body can not feel less than 2,000 volts of static discharge
• Always touch your car before filling up to discharge static electricity