Second law of thermodynamics
What Second law of thermodynamics means in Physics A-Level, as defined for AQA.
Definitions of Second law of thermodynamics
Exam boards and our study guides word this term in slightly different ways. Learn the version your board uses.
Check what you remember
Read the wording for your board, then hide it and explain Second law of thermodynamics in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: AQA
It forbids a device that converts a single thermal reservoir entirely into work with no sink, so efficiency is always below 1.
Forbids a cyclic engine from converting all absorbed heat into work, so efficiency is always below 1.
Topics that use Second law of thermodynamics
- Second Law and engines (A-level only) (AQA A-Level)
Related terms
Using Second law of thermodynamics in the exam
Check the command word and mark scheme for your exact question. After comparing your explanation with the reference, use the term in an answer on the linked topic. This practice does not predict an exam mark.
Practise Physics questions
Create a free account to answer exam-style questions on this topic and get feedback on your answers.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge