When a 12 Ω 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 Ω
2. 36 Ω
3. 48 Ω
4. 60 Ω
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 ohm |
2. | Less than 10 ohm |
3. | More than 10 ohm |
4. | We cannot definitely say |
A galvanometer with a resistance of 36 Ω is changed into an ammeter by using a shunt of 4 Ω. The fraction f0 of total current passing through the galvanometer will be:
1.
2.
3.
4.
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.
2.
3. Zero
4. Infinite
The magnetic induction at point P, which is 4 cm from a long current-carrying wire is 10-8 Tesla. What would be the field of induction at a distance of 12 cm from the same current?
1. | 3.33 x 10-9 Tesla |
2. | 1.11 x 10-4 Tesla |
3. | 3 x 10-3 Tesla |
4. | 9 x 10-2 Tesla |
Two straight horizontal parallel wires carry the same current in the same direction, and d is the distance between them. You are given a small magnetic needle that is freely suspended. Which of the following positions will have the needle's orientation independent of the magnitude of the current in the wires?
1. | At a distance d/2 from any of the wires in any plane. |
2. | At a distance 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 r1 and r2 in which a current i is flowing. The magnetic induction at the centre of O will be:
1.
2.
3.
4.
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. | \(\frac{\mathrm{i} \Delta \mathrm{l} \sin (\theta)}{\mathrm{r}^2} \) | 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. | \(\frac{\mu_0}{4 \pi} \mathrm{i} \Delta \mathrm{l} \sin (\theta)\) |
What is the magnetic field at point O in the figure?
1.
2.
3.
4.