Deformation is a very important topic in Physics and therefore, you should know some key points regarding the topic.

The blog will provide you O Level Physics Deformation notes in detail to make your concepts clear (regarding the topic).

Enough introductions, let’s dive into the topic.

O Level Physics deformation notes

What is Deformation:

Deformation attributes to the change in the size or shape of something. Therefore, deformation is any process that changes the shape, size, or volume of an object.

The type of deformation that happens is based on the type of stress and some other factors. 

There are various types of deformation but we need to understand elastic deformation and plastic deformation for our GCE O Level Physics syllabus.

To understand deformation, you need to understand some common terms such as stress and strain.

This stress is not what a school or a college student faces. In fact, this term refers to the amount of force applied over an area. Moreover, the strain is a force tending to pull or stretch something to an extreme degree.

Elastic Deformation:

An object changes its size and shapes during elastic deformation. However, when the applied force is removed from the object, it returns to its original shape and position.

To understand this, let’s take an example of a spring. When force is applied, it changes its shape but when the force is removed, the spring returns to its original position.

Here you need to understand one formula which is:


This formula shows that force is directly proportional to the spring stretch or compression (x). The more the force is applied, the higher the extension of the object.

It can be written as F=-Kx (where k represents constant). This formula is what we know as “Hooke’s Law”.

See: O Level Report Writing Sample (Directed Writing)

Hooke’s Law:

O Level Physics Deformation notes
Hooke’s Law

Hooke’s law states that the strain in a solid is directly proportional to the applied stress within the elastic limit (a limit till a solid can be stressed, after that it gets deformed) of that solid.

According to Wikipedia, Hooke’s law is a law of physics that says that the force required to stretch or compress a spring by some distance (x) scales linearly with regard to that distance—that is, where k is a fixed factor component of the spring, and x is small related to the whole possible deformation of the spring

Plastic Deformation:

You need to understand this term as it is required by your CIE syllabus. In plastic deformation, an object is permanently damaged.

The object does not return to its original shape, size or position even when the force stops acting on it. To elaborate plastic deformation, let’s take an example of a spring.

If you stretch a spring with a lot of force, there will be one point from where it will not return back to its original position. The spring thus will be deformed (plastic deformation).

Misconceptions: A common misunderstanding is that all substances that bend are “weak” and those that don’t are “strong”. In truth, numerous substances that experience large elastic and plastic deformations, like steel, are capable to absorb stresses that would cause brittle materials, such as glass, with minimal plastic deformation ranges, to break.

When discussing deformation, one commonly used term is elasticity. Well, what is elasticity? Let’s find out!

The Concept of Elasticity in Physics:

Elasticity refers to the ability of an object to resist distorting influence and return back to its original size, shape or position after the force is removed.

Quite similar to what we have discussed above? Well, that is the reason they are in the same topic.

The concept of elasticity is completely opposite to plasticity as discussed above.

When an object faces external resistance, it faces internal resistance that allows the object to return back to its shape after the force is removed.

This internal resistance is what explains the concept of elasticity.

What is exactly required by your CIE syllabus? Let’s discuss it.

  • state that a force may produce a change in the size and shape of a body.
  • plot, draw and interpret extension-load graphs for an elastic solid and describe the associated experimental procedure.
  • recognise the significance of the term “limit of proportionality” for an elastic solid (an understanding of the elastic limit is not required).
  • calculate extensions for an elastic solid using proportionality.

Source: Cambridge Assessment International Education

More on O Level Physics Deformation Notes:

For a given spring and other elastic objects, the extension is directly proportional to the force applied. For instance, if the force is doubled, the extension also doubles. This phenomenon operates until the limit of proportionality is exceeded.

Deformation o level

After the limit of proportionality, this does not work as there is no more linear change in the spring.

The limit of proportionality is the point beyond which Hooke’s law does not work. The elastic limit of spring the maximum point till that spring can be stretched.

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Now, let’s talk about the load-extension graphs. What do you think is the relation between load and extension?

Let me tell. What if you attach some load to a spring. Will it stretch? Yes, of course it will. Then what does this shows? This shows that extension is directly proportional to the load until the limit of proportionality is reached.

Remember (as discussed above), after the limit of proportionality, the Hooke’s law does not apply.

What’s next? What formula you need to know for this topic. The formula you need to know for this topic is F=kx where F refers to force, k refers to constant and x refers to extension.


To conclude, O Level Physics Deformation notes have been provided. Moreover, your Cambridge requirements are also listed above.

Remember to practice some past paper questions to ace the topic. Deformation questions can be found in Paper 1 and Paper 2 both.

This topic has a strong correlation with other topics such as dynamics. Therefore, you should not leave it.

Thank You very much for reading the blog.

Also Read: O Level Chemistry Periodic Table Notes (Revision)


  1. Anonymous says:

    This was very helpful for my upcoming physics test thankyou

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