Bar Magnet - NEET Physics Questions
Question 1: easy

Following figures show the arrangement of bar magnets in different configuration. Each
magnet has magnetic dipole moment \[\overrightarrow{m}\] . Which configuration has highest net magnetic dipole moment?

1.
2.
3.
4.
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Question 2: moderate

A bar magnet of length ‘l’ and magnetic dipole moment ‘M’ is bent in the form of an arc as
shown in figure. The new magnetic dipole moment will be :

1. M/2
2. M
3. \[\frac{3}{\pi}M\]
4. \[\frac{2}{\pi}M\]
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Question 3: difficult

A plastic disc of radius R has a charge q uniformly distributed over its surface. If the disc is rotated with a frequency f about its axis. then magnetic dipole moment will be :

1. \[\frac{\pi qfR^{2}}{2}\]
2. πqfR²
3. 2πqfR²
4. 4πqfR²
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Question 4: moderate

A loop carrying current I lies in the x–y plane as shown in the figure. The unit vector ˆk is coming out of the plane of the paper. The magnetic moment of the current loop is :

1. \[a^{2}I\hat{k}\]
2. \[\left( \frac{\pi}{2}+1 \right)a^{2}I\hat{k}\]
3. \[-\left( \frac{\pi}{2}+1 \right)a^{2}I\hat{k}\]
4. \[\left( 2\pi+1 \right)a^{2}I\hat{k}\]
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Question 5: moderate

As shown in the figure, the radius of each of quarter circular arc is 2m. Find the magnetic moment of the given loop for the current in the loop :

1. 5πi
2. 4πi
3. 2πi
4. 3πi
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Question 6: easy

A loop in the shape of an equilateral triangle of side l is suspended between the pole pieces of a
permanent magnet such that \[\overrightarrow{B}\] is in plane of the loop. If due to a current i in the triangle a torque τ acts on it, the side l of the triangle is :

1. \[\frac{2}{\sqrt{3}}.\left( \frac{\tau}{Bi} \right)\]
2. \[\frac{1}{\sqrt{3}}.\frac{\tau}{Bi}\]
3. \[2\left( \frac{\tau}{\sqrt{3}Bi} \right)^{1/2}\]
4. \[\frac{2}{\sqrt{3}}.\left( \frac{\tau}{Bi} \right)^{1/2}\]
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Question 7: moderate

Find out magnetic dipole moment of given current loop.

1. \[\frac{\pi Ia^{2}}{2}\]
2. \[\frac{\pi Ia^{2}}{4}\]
3. πIa²
4. Zero
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Question 8: moderate

In the given diagram, ratio of magnetic field at point A and B will be :

1. 8
2. 1/2√2
3. 3
4. 4
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Question 9: moderate

In the given diagram a rod is rotating with angular velocity ω. Mass of this rod is m, charge q, and length is l then find out magnetic moment of this rod :

1. \[\frac{q\omega l^{2}}{6}\]
2. \[\frac{q\omega l^{2}}{2}\]
3. \[\frac{q\omega l^{2}}{3}\]
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Question 10: moderate

A current carrying loop is placed in a uniform magnetic field in four different orientations, I, II, III & IV arrange them in the decreasing order of potential Energy :

1. I > III > II > IV
2. I > II > III > IV
3. I > IV > II > III
4. III > IV > I > II
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