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Q. No.
Subtopic: Magnetic Field & Field Lines |
92%
Level 1: 80%+
Hints
A \(100\)-turn coil of wire of size \(2~\text{cm}\times 1.5~\text{cm}\) is suspended between the poles of a magnet producing a field of \(1~\text T,\) inside a galvanometer. Calculate the torque on the coil due to a current of \(0.1~\text{A}\) passing through the coil.
1. \(3 \times 10^{-5}\) N-m
2. \(30\) N-m
3. \(3 \times 10^{-3}\) N-m
4. \(3 \times 10^{-2}\) N-m
1. \(3 \times 10^{-5}\) N-m
2. \(30\) N-m
3. \(3 \times 10^{-3}\) N-m
4. \(3 \times 10^{-2}\) N-m
Subtopic: Bar Magnet |
81%
Level 1: 80%+
Hints
There are two materials \(A\) and \(B\). The material \(B\) have high coercivity and \(A\) have low coercivity. The hysteresis loop area of material \(A\) is lesser than the material \(B\). Then:
| 1. | material \(A\) is preferred for making electromagnets. |
| 2. | material \(B\) is preferred for making permanent magnets. |
| 3. | material \(A\) is preferred for using electric generators and transformers. |
| 4. | all of these. |
Subtopic: Magnetization & Magnetic Intensity |
82%
Level 1: 80%+
Hints
Two identical bar magnets are kept as shown in the figure. The direction of the resultant magnetic field, indicated by the arrowhead at the point \(P\) is:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Magnetic Field & Field Lines |
55%
Level 3: 35%-60%
Hints
A magnet of magnetic dipole moment \(10\hat{i}~\text{A-m}^2\) is placed along the x-axis in a magnetic field \(\vec B=(\hat i+2\hat j)~\text{T}.\) The torque acting on the magnet is:
| 1. | \((30\widehat k)~\text{N-m}\) | 2. | \((10\widehat i+20\widehat j)~\text{N-m}\) |
| 3. | \((20\widehat k)~\text{N-m}\) | 4. | \((-30\widehat k)~\text{N-m}\) |
Subtopic: Magnetic Moment |
87%
Level 1: 80%+
Hints
A current-carrying loop is placed in magnetic field as shown in figure. What is the time period of small oscillation about an axis passing through diameter of the coil?
(Mass of coil is \(m\), radius is \(R\))
(Mass of coil is \(m\), radius is \(R\))
| 1. | \(2 \pi \sqrt{\dfrac{m}{I B}} \) | 2. | \( \sqrt{\dfrac{2 \pi m}{I B}} \) |
| 3. | \( 2 \pi \sqrt{\dfrac{I}{m B}}\) | 4. | \(2 \pi \sqrt{\dfrac{m}{2 / B}}\) |
Subtopic: Analogy between Electrostatics & Magnetostatics |
Level 3: 35%-60%
Hints
Subtopic: Magnetic Field & Field Lines |
54%
Level 3: 35%-60%
Hints
Subtopic: Magnetization & Magnetic Intensity |
84%
Level 1: 80%+
Hints
Needles \(N_1\), \(N_2\) and \(N_3\) are made of ferromagnetic, paramagnetic, and diamagnetic substances respectively. A magnet, when brought close to them, will:
| 1. | attract all three of them |
| 2. | attract \(N_1\) and \(N_2\) strongly but repel \(N_3\) weakly |
| 3. | attract \(N_1\) strongly, \(N_2\) weakly and repel \(N_3\) weakly |
| 4. | attract \(N_1\) strongly, but repel \(N_2\) and \(N_3\) weakly |
Subtopic: Magnetic Materials |
90%
Level 1: 80%+
Hints
Assume that the magnetic field of the earth is due to a small magnetic dipole, placed at the centre of the earth (radius: \(R\)). The magnetic field at the equator is \(B_e.\) The dipole moment of the dipole is:
| 1. | \(\dfrac{\pi}{\mu_0}\left(B_eR^3\right )\) | 2. | \(\dfrac{2\pi}{\mu_0}\left(B_eR^3\right )\) |
| 3. | \(\dfrac{4\pi}{\mu_0}\left(B_eR^3\right )\) | 4. | \(\dfrac{2}{\mu_0}\left(B_eR^3\right )\) |
Subtopic: Bar Magnet |
69%
Level 2: 60%+
Hints
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