2) electricity

• • the ampere (A) is the unit of current
  • the coulomb (C) is the unit of charge
  • the joule (J) is the unit of energy
  • the ohm (Ω) is the unit of resistance
  • the second (s) is the unit of time
  • the volt (V) is the unit of voltage
  • the watt (W) is the unit of power.
• what does “resistance” mean?

  Like a roadblock for the flow of the current
• Electric current is the rate of flow charge. Measured in (A) amps / amperes

  • in other words, the size of an electric current is the amount of charge passing thru the component per second
• conventional current is when:

  • current flows from the positive terminal to the negative terminal of a circuit

  ———

  Electron current is when:

  • The electrons flow from the negative terminal to the positive terminal
• Wires in an electrical circuit are made of metal, bc they are good conductor of electrical current.
• equation to calculate charges: Q = It

  
• Equation to calculate Resistances: R=V/I
• Equation to calculate potential difference: V=IR
• Equation to calculate Power: P=IV
• • Voltage is what drives the current around the circuit. Kind of like "electrical pressure". You may also see it called potential difference.
• Circuit diagram

  shows how components are connected together
• 230V, 50Hz AC supply


  Mains electricity in the UK
• electric current that reverses its direction of flow in a regular pattern (positive to negative)

  AC current (alternating current)
• Electrons move at an even rate and flow in one direction

  DC current (direct current)
• The brown wire in an electrical cable that carries an alternating potential difference from the mains (230v)

  live wire
• a wire that carries current away from the component (0v) ; it is coated in blue plastic

  Neutral wire
• the wire in a mains cable used to connect the metal case of an appliance to earth its a safety wire (0v) green and yellow stripes

  Earth wire