Limit of Proportionality - GCSE Physics Definition

Reviewed by: Leander Oates

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What is the limit of proportionality?

In GCSE Physics, the limit of proportionality refers to the point on a force-extension graph where a material stops obeying Hooke's law. Hooke's law states that the extension of a material is directly proportional to the applied force, meaning that if the force doubles, the extension doubles as well.

Graph showing a force-extension curve with a linear region, non-linear region, and limit of proportionality marked.
Force-extension graph showing the linear region where the extension of the material is directly proportional to the force applied, and the non-linear region beyond the limit of proportionality

Beyond the limit of proportionality, Hooke's law no longer applies; the extension and force applied are no longer directly proportional.

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Leander Oates

Reviewer: Leander Oates

Expertise: Physics

Leander graduated with First-class honours in Science and Education from Sheffield Hallam University. She won the prestigious Lord Robert Winston Solomon Lipson Prize in recognition of her dedication to science and teaching excellence. After teaching and tutoring both science and maths students, Leander now brings this passion for helping young people reach their potential to her work at SME.

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