When a positively charged particle moves in an x-y plane, its path abruptly changes due to the presence of electric and/or magnetic fields beyond P. The curved path is depicted in the x-y plane and is discovered to be noncircular. Which of the following combinations is true?
1. \(\overrightarrow{\mathrm{E}}=0 ; \overrightarrow{\mathrm{B}}=\mathrm{b} \hat{\mathrm{i}}+\mathrm{c} \widehat{\mathrm{k}}\)
2. \(\overrightarrow{\mathrm{E}}=\mathrm{ai} ; \overrightarrow{\mathrm{B}}=\mathrm{c} \widehat{\mathrm{k}}+\mathrm{a} \hat{\mathrm{i}}\)
3. \(\vec{E}=0 ; \vec{B}=c \hat{j}+b \widehat{k}\)
4. \(\overrightarrow{\mathrm{E}}=\mathrm{ai} ; \overrightarrow{\mathrm{B}}=c \widehat{\mathrm{k}}+\mathrm{b} \hat{\mathrm{j}}\)
Two insulated rings, one of a slightly smaller diameter than the other, are suspended along their common diameter as shown. Initially, the planes of the rings are mutually perpendicular. What happens when a steady current is set up in each of them?
1. | the two rings rotate into a common plane. |
2. | the inner ring oscillates about its initial position. |
3. | the inner ring stays stationary while the outer one moves into the plane of the inner ring. |
4. | the outer ring stays stationary while the inner one moves into the plane of the outer ring. |
A charge Q is uniformly distributed on a ring of radius R made of an insulating material. If the ring rotates about the axis passing through its centre and normal to the plane of the ring with constant angular speed ω, then what will be the magnitude of the magnetic moment of the ring?
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Two long parallel copper wires carry currents of 5 A each in opposite directions. If the wires are separated by a distance of 0.5 m, then the force between the two wires will be:
1. | \(10^{-5} \mathrm{~N} \), attractive |
2. | \(10^{-5} \mathrm{~N} \), repulsive |
3. | \(2 \times 10^{-5} N\), attractive |
4. | \(2 \times 10^{-5} N\), repulsive |
A long wire A carries a current of 10 A. Another long wire B, which is parallel to A and separated by 0.1 m from A, carries a current of 5 A, in the opposite direction to that in A. What is the magnitude and nature of the force experienced per unit length of B?
1. | Repulsive force of \(10^{-4} \mathrm{~N} / \mathrm{m}\) |
2. | Attractive force of \(10^{-4} \mathrm{~N} / \mathrm{m}\) |
3. | Repulsive force of \(2 \pi \times 10^{-5} \mathrm{~N} / \mathrm{m}\) |
4. | Attractive force of \(2 \pi \times 10^{-5} \mathrm{~N} / \mathrm{m}\) |
What is the relation between voltage sensitivity (σv) and current sensitivity (σi) of a moving coil galvanometer? (Resistance of Galvanometer = G)
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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. | \(R \over 2\) |