Electricity

• Metals are good conductors of electricity. This means they let electricity pass through them.
• Plastics and rubber are very good insulators of electricity. This means they do not allow electricity to pass through them.
• For electricity to flow, it needs to be a complete circuit (have no gaps).
• cell/battery

  • pushes the electricity around the circuit
  • provides the power
• bulb/lamp

  • light up when electric current passes through it
• ammeter

  • measure the electric current
• voltmeter

  • measures the potential difference
• motor

  • spins around (or moves) to make other objects move
• switch

  • when closed, the switch completes the circuit
  • when open, it stops the flow of electric current
• buzzer

  • makes a sound when complete
• series circuit

  only one pathway for the current to flow (in one loop)
• parallel circuit

  more than one pathway or has multiple branches for the current to flow
• current

  flow of electricity
• electrons

  charges that transfer energy from the battery to the component
• When we measure current, we measure the amount of charge that is flowing through the wire every second. This is measured with an ammeter. Ammeters are connected in series.
• Unit for current

  Amps/Ampere
• Unit symbol for current

  A
• In a series circuit, the current is the same everywhere. In a parallel circuit, the current in each branch adds together to equal the current coming from the battery.
• Potential difference tells you how much energy the battery transfers to the circuit components. This is measured by a voltmeter.
• Unit for potential difference

  volts
• Unit symbol for potential difference

  v
• In a series circuit, the voltmeter is connected in parallel across the component.
• In a series circuit, the potential difference across the cell is equal to the potential difference across all of the other components added together.
• resistance

  measure of how hard it is for current to flow through an electrical component
• Resistance is measured in ohms
• When current is flowing, the moving electrons collide with the fixed metal ions in the wire. Collisions between electrons and fixed ions cause resistance.
• the equation for resistance:

  p.d = current x resistance

  current = p.d/resistance

  resistance = $p.d/current$