- 1(current)
Q. No.A long solenoid carrying a current produces a magnetic field \(B\) along its axis. If the current is doubled and the number of turns per cm is halved, then the new value of the magnetic field will be equal to:
1. \(B\)
2. \(2B\)
3. \(4B\)
4. \(\dfrac B 2\)
1. \(B\)
2. \(2B\)
3. \(4B\)
4. \(\dfrac B 2\)
Subtopic: Ampere Circuital Law |
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Level 1: 80%+
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An infinitely long hollow conducting cylinder with radius \(R\) carries a uniform current along its surface. The correct representation of magnetic field (\(B\)) as a function of radial distance (\(r\)) from the axis of the cylinder is:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Ampere Circuital Law |
65%
Level 2: 60%+
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Given below are two statements :
In the light of the above statements, choose the correct answer from the options given below:
| Statement I: | When currents vary with time, Newton's third law is valid only if momentum carried by the electromagnetic field is taken into account. |
| Statement II: | Ampere's circuital law does not depend on Biot-Savart's law. |
In the light of the above statements, choose the correct answer from the options given below:
| 1. | Both Statement I and Statement II are false |
| 2. | Statement I is false, but Statement II is true. |
| 3. | Both Statement I and Statement II are true. |
| 4. | Statement I is true, but Statement II is false. |
Subtopic: Ampere Circuital Law |
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Level 3: 35%-60%
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The figure \(A\) and \(B\) shows long straight wires of circular cross–section (\(a\) and \(b\) with \(a < b\)), carrying current \(I\) which is uniformly distributed across the cross-section. The magnitude of the magnetic field \(B\) varies with radius \(r\) and can be represented as:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Ampere Circuital Law |
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The figure shows two long co-axial cylindrical cables, carrying the same current along their wall in opposite directions. The magnetic field will be zero at the point is:
| 1. | none of the points | 2. | \(A\) and \(B\) |
| 3. | \(A\) and \(C\) | 4. | \(B\) and \(C\) |
Subtopic: Ampere Circuital Law |
Level 4: Below 35%
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A long straight wire of a circular cross-section with radius a carries a steady current \(I.\) The current \(I\) is uniformly distributed across this cross-section. The plot of magnitude of magnetic field \(B\) with distance \(r\) from the centre of the wire is given by -
| 1. |  |
| 2. |  |
| 3. |  |
| 4. |  |
Subtopic: Ampere Circuital Law |
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\(N\) equally spaced charges each of value \(q,\) are placed on a circle of radius \(R.\) The circle rotates about its axis with an angular velocity \(\omega\) as shown in the figure. A bigger Amperian loop \(B\) encloses the whole circle where as a smaller Amperian loop \(A\) encloses a small segment. The difference between enclosed currents, \(I_A-I_B,\) for the given Amperian loops is:
1. \(\dfrac {2\pi}{N}q\omega\)
2. \(\dfrac {N}{2\pi}q\omega\)
3. \(\dfrac {N}{\pi}q\omega\)
4. \(\dfrac {N^2}{2\pi}q\omega\)
1. \(\dfrac {2\pi}{N}q\omega\)
2. \(\dfrac {N}{2\pi}q\omega\)
3. \(\dfrac {N}{\pi}q\omega\)
4. \(\dfrac {N^2}{2\pi}q\omega\)
Subtopic: Ampere Circuital Law |
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A thin transparent film with refractive index \(1.4,\) is held on circular ring of radius \(1.8 ~\text{cm}.\) The fluid in the film evaporates such that transmission through the film at wavelength \(560 ~\text {nm}\) goes to a minimum every \(12\) seconds. Assuming that the film is flat on its two sides, the rate of evaporation is \(\pi \times 10^{-13} \mathrm{~m}^3 / \mathrm{s}. \)
1. \(1.9\)
2. \(3.8\)
3. \(1.0\)
4. \(38\)
1. \(1.9\)
2. \(3.8\)
3. \(1.0\)
4. \(38\)
Subtopic: Ampere Circuital Law |
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A long cylindrical conductor with large cross section carries an electric current distributed uniformly over its cross-section. Magnetic field due to this current is:
Choose the correct answer from the options given below:
1. \(\mathrm{D}\) Only
2. \(\mathrm{A,D}\) Only
3. \(\mathrm{B,C}\) Only
4. \(\mathrm{E}\) Only
| \(\mathrm{A.}\) | maximum at either ends of the conductor and minimum at the midpoint |
| \(\mathrm{B.}\) | maximum at the axis of the conductor |
| \(\mathrm{C.}\) | minimum at the surface of the conductor |
| \(\mathrm{D.}\) | minimum at the axis of the conductor |
| \(\mathrm{E.}\) | same at all points in the cross-section of the conductor |
1. \(\mathrm{D}\) Only
2. \(\mathrm{A,D}\) Only
3. \(\mathrm{B,C}\) Only
4. \(\mathrm{E}\) Only
Subtopic: Ampere Circuital Law |
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