Magnetic Properties of Matter JEE Main previous year questions with solutions

5 solved JEE Main questions on Magnetic Properties of Matter, free to read — no sign-in needed. The full chapter has 57 questions; sign in to attempt the remaining 52 in the exam simulator.

1. Q1JEE Main 2026 (23 Jan, Shift 1)Magnetic Materials and their Properties
   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 :
   1. A.(A) is true but (R) is false
   2. B.Both (A) and (R) are true but (R) is not the correct explanation of (A)
   3. C.(A) is false but (R) is true
   4. D.Both (A) and (R) are true and (R) is the correct explanation of (A)
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   Answer: (B)

   Assertion (A) states that individual atoms in a ferromagnetic material possess a magnetic dipole moment and interact to form domains. This is a correct description of the domain theory of ferromagnetism, where exchange interactions lead to spontaneous alignment of moments within small regions called domains. Reason (R) states that at high temperatures (above the Curie temperature $T_C$), the domain structure disintegrates due to thermal agitation, and the material becomes paramagnetic. This is also a correct statement regarding the temperature dependence of ferromagnetic materials. However, Reason (R) describes the effect of temperature on the domain structure, whereas Assertion (A) describes the fundamental nature and formation of domains in the ferromagnetic state. The disintegration of domains at high temperature is not the reason why they form spontaneously at lower temperatures. Therefore, both statements are true, but (R) is not the correct explanation of (A).
2. Q2JEE Main 2025 (07 Apr, Shift 2)Magnetism and Properties of Magnet
   Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason(R). Assertion (A) : Magnetic monopoles do not exist. Reason (R) : Magnetic field lines are continuous and form closed loops. In the light of the above statements, choose the most appropriate answer from the options given below :
   1. A.Both $(\mathrm{A})$ and $(\mathrm{R})$ are correct but $(\mathrm{R})$ is not the correct explanation of (A)
   2. B.(A) is correct but $(\mathrm{R})$ is not correct
   3. C.Both $(\mathrm{A})$ and $(\mathrm{R})$ are correct and $(\mathrm{R})$ is the correct explanation of (A)
   4. D.(A) is not correct but ( $\mathrm{R}$) is correct
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   Answer: (C)

   Both statements are correct and reason is also the correct explanation of assertion.
3. Q3JEE Main 2017 (02 Apr)Magnetic Equipments
   A magnetic needle of magnetic moment $6.7\times {10}^{-2}A{m}^{2}$ and moment of inertia $7.5\times {10}^{-6}kg{m}^{2}$ is performing simple harmonic oscillations in a magnetic field of $0.01T$. Time taken for $10$ complete oscillations is:
   1. A.$8.76s$
   2. B.$6.65s$
   3. C.$8.89s$
   4. D.$6.98s$
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   Answer: (B)

   Time period of oscillating magnetic needle is $T=2\pi \sqrt{\dfrac{I}{MB}}$ $=2\pi \sqrt{\dfrac{7.5\times {10}^{-6}}{6.7\times {10}^{-2}\times 0.01}}\sec$ $=0.6647\sec$ Time for oscillations, $t=10T=6.647\sec ⁡=6.65\sec$
4. Q4JEE Main 2026 (04 Apr, Shift 2)Magnetism and Properties of Magnet
   A solenoid has a core made of material with relative permeability $400$. The magnetic field produced in the interior of solenoid is $1.0$ T. The magnetic intensity in SI units is $\alpha \times 10^5$. The value of $\alpha$ is ______. (Free space permeability $\mu_0=4\pi \times 10^{-7}$ SI units.)
   1. A.$\dfrac{25}{\pi}$
   2. B.$\dfrac{1}{16\pi}$
   3. C.$\dfrac{1}{\pi}$
   4. D.$\dfrac{1}{4\pi}$
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   Answer: (B)

   The magnetic field $B$ inside the solenoid is related to the magnetic intensity $H$ by the formula: $B = \mu H = \mu_0 \mu_r H$ Rearranging for $H$, we get: $H = \dfrac{B}{\mu_0 \mu_r}$ Substituting the given values ($B = 1.0$ T, $\mu_r = 400$, and $\mu_0 = 4\pi \times 10^{-7}$ T m/A): $H = \dfrac{1.0}{4\pi \times 10^{-7} \times 400}$ $H = \dfrac{1.0}{1600\pi \times 10^{-7}}$ $H = \dfrac{1}{16\pi \times 10^{-5}}$ $H = \dfrac{1}{16\pi} \times 10^5$ A/m Comparing this with the given expression $H = \alpha \times 10^5$, we find: $\alpha = \dfrac{1}{16\pi}$ Answer: $\dfrac{1}{16\pi}$
5. Q5JEE Main 2025 (07 Apr, Shift 1)Magnetism and Properties of Magnet
   The percentage increase in magnetic field (B) when space within a current carrying solenoid is filled with magnesium (magnetic susceptibility $\left.\chi_{\mathrm{mg}}=1.2 \times 10^{-5}\right)$ is :
   1. A.$\frac{6}{5} \times 10^{-3} \%$
   2. B.$\frac{5}{6} \times 10^{-5} \%$
   3. C.$\frac{5}{6} \times 10^{-4} \%$
   4. D.$\frac{5}{3} \times 10^{-5} \%$
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   Answer: (A)

   $\begin{aligned} & \% \text { change in } B=\frac{B_{\text {new }}-B_{\text {old }}}{B_{\text {old }}} \times 100 \% \\ & =\frac{\mu \mathrm{ni}-\mu_0 \mathrm{ni}}{\mu_0 \mathrm{ni}} \times 100 \%=\frac{\left(\mu-\mu_0\right)}{\mu_0} \times 100 \% \\ & =\frac{\left(\mu_0 \mu_{\mathrm{r}}-\mu_0\right)}{\mu_0} \times 100 \% \\ & =\left(\mu_{\mathrm{r}}-1\right) \times 100 \% \\ & =\chi_{\mathrm{n}} \times 100 \% \\ & =1.2 \times 10^{-3} \%\end{aligned}$