Magnetic Properties of Matter

JEE Main level, single correct, medium

4 of 57

Question 4 of 57

The percentage increase in magnetic field (B) when space within a current carrying solenoid is filled with magnesium (magnetic susceptibility χmg=1.2×10−5)\left.\chi_{\mathrm{mg}}=1.2 \times 10^{-5}\right) is :

Show answer and solution

Answer: (A) 65×10−3%\frac{6}{5} \times 10^{-3} \%

% change in B=Bnew −Bold Bold ×100%=μni−μ0niμ0ni×100%=(μ−μ0)μ0×100%=(μ0μr−μ0)μ0×100%=(μr−1)×100%=χn×100%=1.2×10−3%\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}

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

More Physics practice

JEE Main Physics practice question on Magnetic Properties of Matter (Magnetism and Properties of Magnet), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.