Generating Electricity (Oxford AQA IGCSE Physics)

Revision Note

Generating Electricity

  • Fossil fuels, such as coal and oil, are used to produce energy on-demand when energy is needed

  • This is done by: 

    • Burning the fuel to heat water

    • The water boils creating steam

    • Rising steam is forced around the system and this turns a turbine

    • The turbine turns coils in a magnetic field in the generator

    • This generates electricity in the form of an alternating current using the generator effect

  • The electricity is transferred to the National Grid

  • The steam within the turbine will cool and condense and then be pumped back into the boiler to repeat the process

A coal powered thermal power station

A diagram of a power station using coal. The coal furnace has a series of pipes containing water which pas steam towards a turbine. This is connected to a generator.
The structure of a coal-fired thermal power station
  • Other power stations use different methods of rotating a turbine to generate electricity

    • A wind turbine uses wind to rotate its large turbine, which then turns a coil in a generator

    • A hydroelectric dam uses the passage of water through the dam to rotate its turbine and cause the coil to spin in the generator

    • A geothermal power station uses steam from water pumped underground (which is heated by hot rocks in the Earth's interior) to rotate a turbine

A hydroelectric dam power station

Water passes through the dam, spinning a turbine which is connected to a generator
A hydroelectric dam transfers energy mechanically from the gravitational potential energy store of the water to its kinetic energy store to turn a turbine

A geothermal power station

Water is pumped down to the hot rocks and returns through a fissure as steam, which turns a turbine
Cold water is heated by the rocks and returned as hot water or steam which can be used to turn turbines to generate electricity

Examiner Tip

You don't need to memorise the specifics of each power station. These examples are meant to show you that a wide variety of power stations use the same principles of turning a turbine to generate electricity.

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