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
Hints

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
Hints

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
Hints

advertisementadvertisement

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 |
 54%
Level 3: 35%-60%
NEET - 2024
Hints

The following figures show the arrangement of bar magnets in different configurations. Each magnet has a magnetic dipole. Which configuration has the highest net magnetic dipole moment?

1. 2.
3. 4.
Subtopic:  Bar Magnet |
 71%
Level 2: 60%+
AIPMT - 2014
Hints
Links

A bar magnet of the magnetic moment \(M\) is placed at right angles to a magnetic induction \(B.\) If a force \(F\) is experienced by each pole of the magnet, the length of the magnet will be:
1. \(\dfrac{MB}{F}\) 2. \(\dfrac{BF}{M}\)
3. \(\dfrac{MF}{B}\) 4. \(\dfrac{F}{MB}\)
Subtopic:  Bar Magnet |
 75%
Level 2: 60%+
NEET - 2013
Hints

advertisementadvertisement

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
Hints
Links

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. \(4~\text{mT}\)
Subtopic:  Bar Magnet |
 80%
Level 1: 80%+
NEET - 2024
Hints