Current Electricity

• Static Electricity


  When a charge builds up on an object
• Current Electricity


  The controlled flow of electrons
• An electric circuit is a path for electricity to flow
• Insulators


  • Can build up a static charge by gaining or losing electrons
  • Static charge can't build up on them since electrons can move easily through conductors
• Current


  The flow of electrons from one place to another place
• Electronics


  • Rely on electricity that flows from an energy source through conductors to the devices and back again
• Dry cell battery


  The most common source of electric current to power small electrical devices
• How a battery powers a circuit

  1. Chemical reactions inside the battery give electrons energy as they pass through it from positive end (in) to negative end (out)

  2. The electrons move from the negative part of the battery through the wires

  3. As the electrons pass through the light bulb it will light up

  4. The electrons continue back to the positive end of the battery where they get "recharged" and the cycle restarts
• Electrical Circuit


  A controlled path that electricity flows through, converting electrical energy into another form of energy (e.g., light or sound)
• Parts of an electrical circuit

  • Energy source
  • Load
  • Connectors
  • Switch
• Energy Source


  Any object that provides energy to the circuit (e.g. batteries, outlet)
• Load


  Anything that converts electrical energy to the form or energy needed (e.g. lights, cell phone, appliances)
• Connectors


  Provide a controlled path for electrons to flow to each part of the circuit (almost always wires)
• Switch


  Controls the flow of electrons (can be turned "on" or "off")
• Closed Circuit


  Electrons are flowing, the circuit is operating, the switch is turned "on"
• Open Circuit


  Electrons are NOT flowing, the circuit is NOT operating, the switch is turned "off"
• With the switch open, the circuit is not closed so the current cannot flow and the bulb will NOT light up
• With the switch closed, the circuit is closed so the current can flow and the bulb WILL light up
• Circuit Diagram Symbols - Energy Sources

  • Cell
  • Battery
  • Wall outlet
• Circuit Diagram Symbols - Loads

  • Light bulb
  • Motor
  • Resistor
• Circuit Diagram Symbols - Control & Safety Devices

  • Switch
  • Fuse
  • Ground connection
• Circuit Diagram Symbols - Measurement Devices


  • Voltmeter
  • Ohmmeter
  • Ammeter
• The circuit should have a rectangular shape, even though the wires may not be arranged that neatly
• The circuit should not have any gaps, unless there is an open switch
• Use straight lines for conducting wires
• Do not put any components in the corners