Heating in Circuits (Edexcel GCSE Physics) : Revision Note

The Heating Effect of Current

• When charge passes through a component, such as a resistor, some of the energy is transferred from the electrons to the component by heating, therefore increasing its temperature

  • The energy will dissipate (spread out) into the environment via thermal conduction, convection and radiation

• This is used to an advantage to by devices like electric heaters

The heating effect of current can be used for many applications such as electric heaters

• However, wasted thermal energy makes a device less efficient and if too much current flows through a component, the heating effect can be very dangerous

  • This can burn someone if they touch it or cause a fire

Dissipation of Thermal Energy

• When an electrical current does work against electrical resistance:

  • Electrical energy is dissipated as thermal energy in the surroundings

  • The heat that is produced will dissipate via thermal conduction, convection and radiation

• The amount of heat produced depends on two factors:

  • Current: The greater the current, the more heat that is produced

  • Resistance: The higher the resistance, the more heat that is produced (for a given current)

• Note that reducing the resistance can cause the current to increase

  • This could actually increase the amount of heat produced