Q. No.
What is a representation of the magnetic field caused by a straight conductor with a uniform cross-section and a steady current of radius 'a'?
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A current-carrying wire is placed in a uniform magnetic field in the shape of the curve \(y= \alpha sin ({\pi x \over L}),~0 \underline{<}x \underline{<}~2L\)
. What will be the force acting on the wire?
| 1. | \(iBL \over \pi\) | 2. | \(iBL \pi\) |
| 3. | \(2iBL \) | 4. | Zero |
A circular coil is in the y-z plane with its centre at the origin. The coil carries a constant current. Assuming the direction of the magnetic field at x = – 25 cm to be positive, which of the following graphs shows the variation of the magnetic field along the x-axis?
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A particle of charge +q and mass m moving under the influence of a uniform electric field and a uniform magnetic field follows a trajectory from P to Q as shown in the figure. The velocities at P and Q are and respectively. Which of the following statement(s) is/are correct?
| 1. | \(\mathrm{E}=\frac{3}{4} \frac{\mathrm{mv}^2}{\mathrm{qa}}\) |
| 2. | Rate of work done by electric field at P is\(\frac{3}{4} \frac{\mathrm{mv}^3}{\mathrm{a}}\) |
| 3. | Rate of work done by both fields at Q is zero |
| 4. | All of the above |
A particle with charge q, moving with a momentum p, enters a uniform magnetic field normally. The magnetic field has magnitude B and is confined to a region of width d, where . The particle is deflected by an angle in crossing the field, then:
| 1. | \(\sin \theta={Bqd \over p}\) | 2. | \(\sin \theta={p \over Bqd}\) |
| 3. | \(\sin \theta={Bp \over qd}\) | 4. | \(\sin \theta={pd \over Bq}\) |
What will happen if two thin, long parallel wires separated by a distance "d" carry current "i" in the same direction?
| 1. | attract each other with a force per unit length of |
| 2. | repel each other with a force per unit length of |
| 3. | attract each other with a force per unit length of |
| 4. | repel each other with a force per unit length of |
A long straight wire of radius 'a' carries a steady current I. The current is uniformly distributed over its cross-section. The ratio of the magnetic fields B and B' at radial distances a/2 and 2a respectively, from the axis of the wire, is:
| 1. | 1/2 | 2. | 1 |
| 3. | 4 | 4. | 1/4 |
A current loop consists of two identical semicircular parts each of radius \(R\), one lying in the x-y plane, and the other in the x-z plane. If the current in the loop is \(i\), what will be the resultant magnetic field due to the two semicircular parts at their common centre?
| 1. | \( \frac{\mu_0 i}{2 \sqrt{2} R} \) | 2. | \( \frac{\mu_0 i}{2 R} \) |
| 3. | \( \frac{\mu_0 i}{4 R} \) | 4. | \( \frac{\mu_0 i}{\sqrt{2} R}\) |
Which one of the following gives the value of the magnetic field according to Biot-Savart’s law?
| 1. | \(\frac{\mathrm{i} \Delta \mathrm{l} \sin (\theta)}{\mathrm{r}^2} \) | 2. | \(\frac{\mu_0}{4 \pi} \frac{\mathrm{i} \Delta \mathrm{l} \sin (\theta)}{\mathrm{r}} \) |
| 3. | \(\frac{\mu_0}{4 \pi} \frac{\mathrm{i} \Delta \mathrm{l} \sin (\theta)}{\mathrm{r}^2} \) | 4. | \(\frac{\mu_0}{4 \pi} \mathrm{i} \Delta \mathrm{l} \sin (\theta)\) |
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