What is the relation between voltage sensitivity (σv) and current sensitivity (σi) of a moving coil galvanometer? (Resistance of Galvanometer = G)
1.
2.
3.
4.
A galvanometer having a coil resistance of \(60~\Omega\) shows full-scale deflection when a current of 1.0 A passes through it. How can we convert it into an ammeter capable of reading currents up to 5.0 A?
1. | putting in series resistance of \(240 ~\Omega \text {. }\) |
2. | putting in parallel resistance of \(240 ~\Omega \text {. }\) |
3. | putting in series resistance of \(15~ \Omega \text {. }\) |
4. | putting in parallel resistance of \(15~ \Omega \text {. }\) |
A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is B. It is then bent into a circular coil of n turns. What will the magnetic field be at the centre of this n-turn coil?
1. | nB | 2. | n2B |
3. | 2nB | 4. | 2n2B |
If an i-ampere current flows through an infinitely long, straight, thin-walled tube, what will be the magnetic induction at any point within the tube?
1. | infinite | 2. | zero |
3. | \( \frac{\mu_0 2 i}{4 \pi} ~\text{T } \) | 4. | \( \frac{\mu_0 i}{2 r} ~\text{T} \) |
If the magnetic field at the centre of the circular coil is B0, then what is the distance on its axis from the centre of the coil where \(B_x=\frac{B_0}{8}~?\)
(R= radius of the coil)
1. | \(R \over 3\) | 2. | \(\sqrt{3}R\) |
3. | \(R \over \sqrt3\) | 4. | \(R \over 2\) |
A charged particle is projected in a uniform magnetic field at an angle of 45° to the magnetic field. If the circumference of the helical path followed by it is 2 cm, then the pitch of the helix will be:
1. 1 cm
2. \(\sqrt{2}\) cm
3. 2 cm
4. 4 cm
A wire of length l carrying current i is folded to form a circular coil of N turns. What should be the value of N to have the maximum value of the magnetic moment in the coil?
1. 1
2. 4
3. 9
4. 10
If charge -Q is moving vertically upwards, then what will be the force on the charged particle if it enters a magnetic field that is pointed towards the south?
1. North
2. South
3. East
4. West
What happens when the number of turns in a galvanometer is doubled?
1. | voltage sensitivity becomes double. |
2. | current sensitivity becomes double. |
3. | voltage sensitivity becomes half. |
4. | current sensitivity remains the same. |
The two parts of the loop are circles of radii 2a and a, respectively, and carry the same current i as shown in the given figure. What is the magnitude of the dipole moment of the current loop?
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2.
3.
4. Zero