P5 revision

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static electricity

Positive charges do not move

  • Moving charge=current
  • When a van der graff generator runs, charge collects on its dome
    • This charge may "jump" in the form of a spark
    • Electricity always takes the shortest route to earth. In this case, through you,
  • Charges are randomly distibuted across everything
    • Rubbing the balloon on your hair generates friction which transfers the negative charges across to the balloon
    • The negatively charged ballon is attracted to the positive charges in the wall, so it sticks.


  • Components in a circuit make it harder for the electrons to flow through, they are said to have resistance.
  • Resistance is a mesure of how much a material tried to stop electrons passing through it.
  • All wires and components have resistance, although the resistance in wires is negligible and can be ignored.
  • Electrons passing through a wire with resistance create heat due to the electrons colliding with statiobary metal ions.
  • Resistors are components designed to reduce the current of a circuit:
    • A variable resistor has a customisable resistance.
    • A fixed resistor has a permanent resistance.
  • Voltage= current X resistance


  • Voltage is a mesure of how much "push" the electrons in a circuit get from the power source. The larger the voltage, the larger the push.
    • AKA. potential difference
  • For a series circuit:
    • The sum of the coltage for each component is equal to the voltage across the cell
      • I.E. V(cell)= V1 + V2
  • .For a parallell circuit, the voltage across each component is the same as the voltage of the cell:
    • I.E. V(cell)=V1=V2
  • Voltage is "used up" by comentents in series, but if it parallell, the voltage is split but stays the same.
  • Voltage= current X resistance

Ohm's law

  • This version of ohm's law states that as voltage increases, the current also increases. The voltage and current are directly propotional whilw the resistance remains the same.
  • For a low resistance material, more current is allowed to flow for a given voltage. For a high resistance material, less current will




is that everything you need to know for c5?



it's p5?

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