Voltage and Current Changes

• Current


  • The flow of charge (electrons), which transfers energy around a circuit
  • Charge flows through a circuit like a river
  • When a circuit is complete and includes an energy source, charged particles are pushed around the circuit via wires
• Insulators 


  • Prevent the flow of electrons
  • That is why wires are sometimes lined with rubber to prevent people from being electrocuted
• Measuring current


  • The amount of current (electrons) that are flowing through a circuit is measured in amperes or amps (A).
  • Higher the amps, the more current flowing, the lower the amps the less current flowing
  • Current is measured using an ammeter
  • Ammeter is placed in line with the other components, unlike the voltmeter which is parallel
• Current in a series circuit

  • If two globes are connected in series, all currents (electrons) pass through both globes
  • Current is the same at all points in a series circuit
  • Current in a series depends on the number of cells (or batteries)
  • The more cells you add, the greater the current
• Current in Parallel


  • If two or more globes are connected in parallel, the current must split
  • This means that the total current is the sum of the currents through each component
  • If one globe stops working, the other globes would still work due to different pathways. Globes, however, won't get brighter because the power supply does not change

  
• Voltage

  • The amount of charge that passes in a circuit in one second
  • It measures the difference in potential energy across an energy source or circuit component (potential difference)
  • Units for voltage is volts(V)
  • If there is a high voltage there is a large potential difference meaning that electrons either lose or gain a lot of energy
  • If there's a low voltage there is a small potential difference meaning that electrons either lose or gain only a small amount of energy
• Measuring Voltage

  • The voltmeter is placed parallel to the source to measure the potential difference between two points
  • In series, voltage is shared between components
  • In parallel, the voltage through each bulb is equal to the supplied voltage (it will be the same as the amps in that section)
  • A parallel circuit would produce brighter light globes because each bulb has equal voltage to the voltage supplied for each component whereas in a series, the bulbs share the voltage