Specific latent heat (L): The energy required to change the state of 1 kg of a substance without changing its temperature. Units: J/kg.
Specific latent heat of fusion (Lf): Energy per kg needed to melt a solid (or freeze a liquid). For water: 334,000 J/kg.
Specific latent heat of vaporisation (Lv): Energy per kg needed to boil a liquid (or condense a gas). For water: 2,260,000 J/kg.
Latent: From Latin meaning "hidden" — it is "hidden" because it changes the state of the substance without changing its temperature, so a thermometer cannot detect it.
Specific heat capacity (c): Energy per kg per degree to change temperature WITHIN a state (contrasted with latent heat which is for state changes at constant temperature).
This definitions covers Key Definitions within Specific Latent Heat for GCSE Physics. Revise Specific Latent Heat in Particle Model for GCSE Physics with 13 exam-style questions and 30 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 6 of 12 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Practice questions for Specific Latent Heat
What is specific latent heat?
During a state change, energy is being supplied to a substance but the temperature does not change. Explain where this energy goes.