Q. No.
When a \(12~\Omega\) resistor is connected in parallel with a moving coil galvanometer, its deflection reduces from \(50\) divisions to \(10\) divisions. What will be the resistance of the galvanometer?
1. \(24~\Omega\)
2. \(36~\Omega\)
3. \(48~\Omega\)
4. \(60~\Omega\)
1. \(24~\Omega\)
2. \(36~\Omega\)
3. \(48~\Omega\)
4. \(60~\Omega\)
If an ammeter \(A\) reads \(2\) A and the voltmeter \(V\) reads \(20\) V, what is the value of resistance \(R\)? (Assuming finite resistances of ammeter and voltmeter)
| 1. | Exactly \(10~\Omega\) |
| 2. | Less than \(10~\Omega\) |
| 3. | More than \(10~\Omega\) |
| 4. | We cannot definitely say |
| 1. | \(\dfrac{1}{40}\) | 2. | \(\dfrac{1}{4}\) |
| 3. | \(\dfrac{1}{140}\) | 4. | \(\dfrac{1}{10}\) |
An infinitely long straight conductor is bent into the shape as shown in the figure.
It carries a current of \(i\) amperes and the radius of the circular loop is \(r\) metres. What will be the magnetic induction at its centre?
1. \(\frac{\mu_{0}}{4 \pi} \frac{2 i}{r} \left( \pi + 1 \right)\)
2. \(\frac{\mu_{0}}{4 \pi} \frac{2 i}{r} \left(\pi - 1 \right)\)
3. zero
4. Infinite
| 1. | \(3.33\times 10^{-9}\) Tesla |
| 2. | \(1.11\times 10^{-4}\) Tesla |
| 3. | \(3\times 10^{-3}\) Tesla |
| 4. | \(9\times 10^{-2}\) Tesla |
| 1. | At a distance \(\frac{d}{2}\) from any of the wires in any plane. |
| 2. | At a distance \(\frac{d}{3}\) from any of the wires in the horizontal plane. |
| 3. | Anywhere on the circumference of a vertical circle of radius \(d\) and centre halfway between the wires. |
| 4. | At points halfway between the wires in the horizontal plane. |
In the figure shown below there are two semicircles of radius \(r_1\) and \(r_2\) in which a current \(i\) is flowing. The magnetic induction at the centre of \(O\) will be:
| 1. | \(\dfrac{\mu_{0} i}{r} \left(r_{1} + r_{2}\right)\) | 2. | \(\dfrac{\mu_{0} i}{4} \left[\dfrac{r_{1} + r_{2}}{r_{1} r_{2}}\right]\) |
| 3. | \(\dfrac{\mu_{0} i}{4} \left(r_{1} - r_{2}\right)\) | 4. | \(\dfrac{\mu_{0} i}{4} \left[\dfrac{r_{2} - r_{1}}{r_{1} r_{2}}\right]\) |
In a current-carrying long solenoid, the field produced does not depend upon:
| 1. | Number of turns per unit length | 2. | Current flowing |
| 3. | Radius of the solenoid | 4. | All of the above |
Which one of the following gives the value of the magnetic field according to Biot-Savart’s law?
| 1. | \(\dfrac{{i} \Delta {l} \sin (\theta)}{{r}^2} \) | 2. | \(\dfrac{\mu_0}{4 \pi} \dfrac{i \Delta {l} \sin (\theta)}{r} \) |
| 3. | \(\dfrac{\mu_0}{4 \pi} \dfrac{{i} \Delta{l} \sin (\theta)}{{r}^2} \) | 4. | \(\dfrac{\mu_0}{4 \pi} {i} \Delta {l} \sin (\theta)\) |
What is the magnetic field at point \(O\) in the figure?
| 1. | \(\dfrac{\mu_{0} I}{4 \pi r}\) | 2. | \(\dfrac{\mu_{0} I}{4 \pi r} + \dfrac{\mu_{0} I}{2 \pi r}\) |
| 3. | \(\dfrac{\mu_{0} I}{4 r} + \dfrac{\mu_{0} I}{4 \pi r}\) | 4. | \(\dfrac{\mu_{0} I}{4 r} - \dfrac{\mu_{0} I}{4 \pi r}\) |
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