Revision Notes

2.2.3 Temperature & Heat

Internal Energy

  • When a substance is heated, its internal energy (sometimes referred to as thermal energy or heat) increases
  • As a substance’s internal energy increases, so will its temperature
    The higher the temperature of a substance, the more internal energy it possesses


kinetic-theory, IGCSE & GCSE Physics revision notes

As the temperature of a substance is increased, the total energy of the molecules (the internal energy) increases


Extended Only

Internal Energy & Molecules

  • The molecules within a substance possess two forms of energy:
    • Kinetic energy (due to their random motion/vibration)
    • Potential energy (due to the bonds between the molecules)
  • Together, these two forms of energy make up the internal (thermal) energy of the substance
  • When a substance is heated, that heat will usually cause the kinetic energy of the molecules to increase
    The temperature of the material is related to the average kinetic energy of the molecules


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