AQA GCSE Energy Transfer in Circuits

Energy transfer in a circuit.

In the circuit above the battery contains a store of chemical energy. 

Work is done (energy transferred) by the battery  to make electrical charges (electrons) flow around the circuit. 

In this case the bulb will act as a resistor because it will have some resistance. 

As the charges flow through the resistor (bulb)  the electrons have to move between the vibrating metal ions of the metal filament in the bulb.

As the electrons collide with the metal ions, they transfer energy to the metal ions. Both the kinetic and thermal energy store of the metal filament in the bulb increases. The metal ions vibrate faster and the bulb becomes hotter.

The work done (energy transferred) by the battery is equal to the total energy transferred to the resistor (bulb).

Many components in a circuit can act as a resistor, because circuit components have resistance. When charge flows through the resistor, energy is transferred and the resistor becomes hotter. This thermal energy store of the resistor is then dissipated to the  thermal energy store of the surroundings.  

A different example

It is also possible that the energy is transferred to a kinetic store, rather than a thermal store. A washing machine uses mains electricity to rotate the drum. So, in this case the mains power supply would increase the kinetic energy store of the motor of the washing machine to make the drum spin