Logo
Jeeify
MCQEasyJEE 2026Types of Magnetic Materials

JEE Physics 2026 Question with Solution

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Consider a ferromagnetic material :

Assertion (A): The individual atoms in a ferromagnetic material possess a magnetic dipole moment and interact with one another in such a way that they spontaneously align themselves forming domains.

Reason (R): At high enough temperature, the domain structure of ferromagnetic material disintegrates. Thus, magnetization will disappear at high enough temperature known as Curie temperature.

In the light of the above statements, choose the correct answer from the options given below :

  • A

    (A) is false but (R) is true

  • B

    Both (A) and (R) are true but (R) is not the correct explanation of (A)

  • C

    Both (A) and (R) are true and (R) is the correct explanation of (A)

  • D

    (A) is true but (R) is false

Answer

Correct answer:B

Step-by-step solution

Standard Method

Given: An assertion and a reason about ferromagnetic materials and Curie temperature.

Find: Whether Assertion (A) and Reason (R) are true, and whether (R) correctly explains (A).

Understanding the concept: Ferromagnetism is characterized by spontaneous magnetization and the formation of domains due to strong exchange interactions between atomic dipoles. The Curie temperature TcT_c marks the transition from ferromagnetic to paramagnetic behavior.

Assertion (A) is true: Ferromagnetism is explained by domain theory where individual atomic dipoles align spontaneously in small regions called domains.

Reason (R) is also true: Increasing temperature increases thermal agitation, which eventually overcomes the alignment forces, causing the material to become paramagnetic at the Curie temperature.

However, (R) describes the disappearance of ferromagnetism at high temperature, while (A) describes the existence and formation of domains. So (R) does not explain why the atoms align in the first place; that is due to exchange interaction.

Therefore, both (A) and (R) are true, but (R) is not the correct explanation of (A).

The correct option is B.

Common mistakes

  • Assuming that because Curie temperature is related to ferromagnetism, the reason must automatically explain the assertion. This is wrong because relevance is not the same as explanation. Check whether (R) actually gives the cause of domain formation; here it only describes how ferromagnetism disappears at high temperature.

  • Thinking that domain formation occurs because of heating effects. This is incorrect because domains form due to exchange interaction between atomic dipoles, while increasing temperature tends to disturb alignment rather than create it.

Practice more Types of Magnetic Materials questions

Get unlimited AI-adaptive practice, mastery tracking, and an AI tutor that explains every step — free to start.

Start free trialMore on Types of Magnetic Materials

Related questions