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Q. No.In a uniform magnetic field of \(0.049~\text T\), a magnetic needle performs \(20\) complete oscillations in \(5\) seconds as shown. The moment of inertia of the needle is \(9.8 × 10^{-6} ~\text{kg m}^2\). If the magnitude of magnetic moment of the needle is \(x \times 10^{-5 }~\text {Am}^2;\) then the value of '\(x\)' is:
| 1. | \(128\pi^2\) | 2. | \(50\pi^2\) |
| 3. | \(1280\pi^2\) | 4. | \(5\pi^2\) |
Subtopic: Bar Magnet |
52%
Level 3: 35%-60%
NEET - 2024
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Match List-I with List-II.
Choose the correct answer from the options given below:
| List-I Material |
List-II Susceptibility \((\chi)\) |
||
| \(\mathrm{(A)}\) | Diamagnetic | \(\mathrm{(I)}\) | \(\chi=0\) |
| \(\mathrm{(B)}\) | Ferromagnetic | \(\mathrm{(II)}\) | \(0>\chi\geq-1\) |
| \(\mathrm{(C)}\) | Paramagnetic | \(\mathrm{(III)}\) | \(\chi\gg1\) |
| \(\mathrm{(D)}\) | Non-magnetic | \(\mathrm{(IV)}\) | \(0<\chi<\varepsilon\) (a small positive number) |
| 1. | \(\text{A-II, B-I, C-III, D-IV}\) | 2. | \(\text{A-III, B-II, C-I, D-IV}\) |
| 3. | \(\text{A-IV, B-III, C-II, D-I}\) | 4. | \(\text{A-II, B-III, C-IV, D-I}\) |
Subtopic: Magnetic Materials |
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Level 2: 60%+
NEET - 2024
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An iron bar of length \( L\) has a magnetic moment \(M.\) It is bent at the middle of its length such that the two arms make an angle \(60^\circ\) with each other. The magnetic moment of this new magnet is:
| 1. | \(\dfrac{M}{2}\) | 2. | \({2 M}\) |
| 3. | \(\dfrac{{M}}{\sqrt{3}}\) | 4. | \(M\) |
Subtopic: Bar Magnet |
53%
Level 3: 35%-60%
NEET - 2024
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The length of a magnetized iron bar is \(L\) and its magnetic moment is \(M.\) When this bar is bent to form a semicircle its magnetic moment is:
| 1. | \(M\) | 2. | \(\dfrac{M\pi}{2}\) |
| 3. | \( \dfrac{M}{2\pi}\) | 4. | \(\dfrac{2M}{\pi}\) |
Subtopic: Bar Magnet |
75%
Level 2: 60%+
NEET - 2024
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Match List-I with List-II
Choose the correct answer from the options given below:
| List-I (Material) | List-II (Example) | ||
| (A) | Diamagnet | (I) | Alnico |
| (B) | Paramagnet | (II) | Copper |
| (C) | Soft ferromagnet | (III) | Aluminium |
| (D) | Hard ferromagnet | (IV) | Gadolinium |
| 1. | A-I, B-II, C-III, D-IV |
| 2. | A-IV, B-III, C-II, D-I |
| 3. | A-III, B-II, C-I, D-IV |
| 4. | A-II, B-III, C-IV, D-I |
Subtopic: Magnetic Materials |
59%
Level 3: 35%-60%
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The best suited curve showing the variations of susceptibility (\(\chi\)) of a paramagnetic material in free space with temperature (\(T\)) is:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Magnetic Materials |
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Level 1: 80%+
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The magnetic potential energy when a magnetic bar with a magnetic moment \(\vec{M}\) is placed perpendicular to the magnetic field \(\vec{B}\) is:
| 1. | \(\dfrac{-mB}{2}\) | 2. | zero |
| 3. | \(-mB\) | 4. | \(mB\) |
Subtopic: Analogy between Electrostatics & Magnetostatics |
75%
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The incorrect relation for a diamagnetic material (all the symbols carry their usual meaning and \(\varepsilon\) is a small positive number) is:
1. \(\mu<\mu_{0}\)
2. \(0\leqslant\mu_{\mathrm{r}}<1\)
3. \(-1\leqslant\chi<0\)
4. \(1<\mu_r<1+\varepsilon\)
1. \(\mu<\mu_{0}\)
2. \(0\leqslant\mu_{\mathrm{r}}<1\)
3. \(-1\leqslant\chi<0\)
4. \(1<\mu_r<1+\varepsilon\)
Subtopic: Magnetic Materials |
60%
Level 2: 60%+
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The magnetic moment and moment of inertia of a magnetic needle as shown are, respectively, \(1.0\times10^{-2}~\text{A m}^{2}~\text{and}~\frac{10^{-6}}{\pi^{2}}~\text{kg m}^{2}.\) If it completes \(10\) oscillations in \(10~\text s,\) the magnitude of the magnetic field is:
1. \(0.4~\text T\)
2. \(4~\text T\)
3. \(0.4~\text{mT}\)
4. \(4~\text{mT}\)
1. \(0.4~\text T\)
2. \(4~\text T\)
3. \(0.4~\text{mT}\)
4. \(4~\text{mT}\)
Subtopic: Magnetization & Magnetic Intensity |
79%
Level 2: 60%+
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The magnetic moment of an iron bar is \(M.\) It is now bent in such a way that it forms an arc section of a circle subtending an angle of \(60^\circ\) at the centre. The magnetic moment of this arc section is:
| 1. | \(\dfrac{3 M}{\pi}\) | 2. | \(\dfrac{4M}{\pi}\) |
| 3. | \(\dfrac{ M}{\pi}\) | 4. | \(\dfrac{2 M}{\pi}\) |
Subtopic: Bar Magnet |
77%
Level 2: 60%+
NEET - 2024
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