Topic 2 Physics: Electricity

• Current


  Measure of the flow of electrons around a circuit
• Potential difference


  Force driving the flow of electrons around a circuit
• Resistance


  Everything in a circuit that resists or opposes the flow of electrons
• Conventional current


  Electrons flow from the negative terminal to the positive terminal
• Current flows


  From positive to negative
• For wires and resistors, increasing the temperature


  Will increase the resistance
• Charge


  Measure of the total current that flowed within a period of time
• The resistance of a thermistor


  Decreases as the temperature increases
• Series circuit


  • PD shared
  • Current same
  • Total resistance equal to sum of resistance of components
  • Components with greater resistance will have a greater share of the voltage
• Parallel circuit


  • PD same
  • Current shared
  • Adding a resistor in parallel with an existing resistor will decrease the overall resistance
• High current


  Causes a lot of wasted heat
• Step-up transformer


  Increases voltage and decreases current
• Step-down transformer


  Decreases voltage and increases current