Calculating Energy Transfers (Edexcel IGCSE Science (Double Award): Physics): Revision Note

Calculating energy transfers

• Work is done when charge flows through a circuit

  • Work done is equal to the energy transferred

• The amount of energy transferred by electrical work in a component (or appliance) depends upon:

  • The current, I

  • The potential difference, V

  • The amount of time the component is used for, t

• When charge flows through a resistor, for example, the energy transferred is what makes the resistor hot

• The energy transferred can be calculated using the equation:

$E=P\times t$

• Where:

  • E = energy transferred in joules (J)

  • P = power in watts (W)

  • t = time in seconds (s)

• P = IV as explained in Electrical power & fuses

  • So this equation can also be written as:

$E=I\times V\times t$

• Where:

  • I = current in amperes (A)

  • V = potential difference in volts (V)

• When charge flows around a circuit for a given time, the energy supplied by the battery is equal to the energy transferred to all the components in the circuit

• You can read more about how energy is transferred in our revision note, Energy Stores & Transfers