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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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: Bar Magnet |
80%
Level 1: 80%+
NEET - 2024
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Due to a small magnet, the intensity at a distance \(x\) in the end-on position is \(9~\text{gauss}\). What will be the intensity at a distance \(\dfrac{x}{2}\) on equatorial position?
| 1. | \(9~\text{gauss}\) | 2. | \(4~\text{gauss}\) |
| 3. | \(36~\text{gauss}\) | 4. | \(4.5~\text{gauss}\) |
Subtopic: Bar Magnet |
74%
Level 2: 60%+
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The unit of pole strength is:
1. \(\text{Am}^2\)
2. \(\text{Am}\)
3. \(\frac{\text{A}^2}{\text{m}}\)
4. \(\frac{\text{A}^2}{\text{m}^2}\)
Subtopic: Bar Magnet |
71%
Level 2: 60%+
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The following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole. Which configuration has the highest net magnetic dipole moment?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Bar Magnet |
70%
Level 2: 60%+
NEET - 2014
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A bar magnet of length \(l\) and magnetic dipole moment \(M\) is bent in the form of an arc as shown in the figure. The new magnetic dipole moment will be:
| 1. | \(\dfrac{3M}{\pi}\) | 2. | \(\dfrac{2M}{l\pi}\) |
| 3. | \(\dfrac{M}{ 2}\) | 4. | \(M\) |
Subtopic: Bar Magnet |
82%
Level 1: 80%+
AIPMT - 2013
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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 |
72%
Level 2: 60%+
NEET - 2024
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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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If a magnetic needle is made to vibrate in uniform field \(H\), then its time period is \(T\). If it vibrates in the field of intensity \(4H\), its time period will be:
| 1. | \(2T\) | 2. | \(\dfrac{T}{2}\) |
| 3. | \(\dfrac{2}{T}\) | 4. | \(T\) |
Subtopic: Bar Magnet |
78%
Level 2: 60%+
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