A charge Q is uniformly distributed on a ring of radius R made of an insulating material. If the ring rotates about the axis passing through its centre and normal to the plane of the ring with constant angular speed ω, then what will be the magnitude of the magnetic moment of the ring?
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A long wire A carries a current of 10 A. Another long wire B, which is parallel to A and separated by 0.1 m from A, carries a current of 5 A, in the opposite direction to that in A. What is the magnitude and nature of the force experienced per unit length of B?
1. | Repulsive force of \(10^{-4} \mathrm{~N} / \mathrm{m}\) |
2. | Attractive force of \(10^{-4} \mathrm{~N} / \mathrm{m}\) |
3. | Repulsive force of \(2 \pi \times 10^{-5} \mathrm{~N} / \mathrm{m}\) |
4. | Attractive force of \(2 \pi \times 10^{-5} \mathrm{~N} / \mathrm{m}\) |
If the magnetic field at the centre of the circular coil is B0, then what is the distance on its axis from the centre of the coil where \(B_x=\frac{B_0}{8}~?\)
(R= radius of the coil)
1. | \(R \over 3\) | 2. | \(\sqrt{3}R\) |
3. | \(R \over \sqrt3\) | 4. | \(R \over 2\) |
What happens when the number of turns in a galvanometer is doubled?
1. | voltage sensitivity becomes double. |
2. | current sensitivity becomes double. |
3. | voltage sensitivity becomes half. |
4. | current sensitivity remains the same. |
The two parts of the loop are circles of radii 2a and a, respectively, and carry the same current i as shown in the given figure. What is the magnitude of the dipole moment of the current loop?
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4. Zero
What is the magnetic moment of the following current loop?
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4. Zero
As indicated, a long, straight conductor XY carrying a current i1 is placed antiparallel to a conductor AB of length l carrying a current i2. How much of a force is acting on AB?
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If a long hollow copper pipe carries a direct current along its length, then the magnetic field associated with the current will be:
1. | Only inside the pipe | 2. | Only outside the pipe |
3. | Both inside and outside the pipe | 4. | Zero everywhere |
Magnetic field at the outer surface of long hollow cylindrical shells of radius R and carrying current I is B. What is the magnetic field at a distance of from the axis of the cylindrical shell?
1. | \(B \over 2\) | 2. | \(2B\) |
3. | \(B \over 4\) | 4. | \(2B \over 3\) |
A charged particle is projected through a region in a gravity-free space. If it passes through the region with constant speed, then the region may have:
1. \(\vec{E}=0, \vec{B} \neq 0\)
2. \(\vec{E} \neq 0, \vec{B} \neq 0\)
3. \(\vec{E} \neq 0, \vec{B}=0\)
4. Both (1) & (2)