### MCQs of Moving Charges & Magnetism

Showing 1 to 10 out of 123 Questions
1.
At a place an electric field and a magnetic field are in the downward direction. There is an electron moves in the downward direction. Hence this electron _____ .
 (a) will bend towards left (b) will bend towards right (c) will gain velocity (d) will lose velocity.
2.
When a charged particle moves in a magnetic field its kinetic energy _____ .
 (a) remains constant (b) can increase (c) can decrease (d) can increase or decrease
3.
There are 100 turns per cm length in a very long solenoid. It carries a current of 5 A. The magnetic field at its centre on the axis is _____ T.
 (a) 3.14 × 10-2 (b) 6.28 × 10-2 (c) 9.42 × 10-2 (d) 12.56 × 10-2
4.
A conducting wire of 1 m length is used to form a circular loop. If it carries a current of 1 ampere, its magnetic moment will be _____ Am2.
 (a) $2\mathrm{\pi }$ (b) $\frac{\mathrm{\pi }}{2}$ (c) $\frac{\mathrm{\pi }}{4}$ (d) $\frac{1}{4\mathrm{\pi }}$
5.
A long wire carries a steady current. When it is bent in a circular form, the magnetic field at its centre is B. Now if this wire is bent in circular loop of n turns, what is the magnetic field at its centre ?
 (a) nB (b) ${\mathrm{n}}^{2}\mathrm{B}$ (c) 2nB (d) $2{\mathrm{n}}^{2}\mathrm{B}$
6.
Two parallel thin wires, each carrying current I are kept at a separation r from each other. Hence the magnitude of force per unit length of one wire due to the other wire is _____
 (a) $\frac{{\mu }_{0}{I}^{2}}{{r}^{2}}$ (b) $\frac{{\mu }_{0}{I}^{2}}{2\mathrm{\pi }r}$ (c) $\frac{{\mu }_{0}I}{2\mathrm{\pi }r}$ (d) $\frac{{\mu }_{0}I}{2\mathrm{\pi }{r}^{2}}$
7.
A particle of charge q and mass m moves on a circular path of radius r in a plane inside and normal to a uniform magnetic field B. The time taken by this particle to complete one revolution is _____ .
 (a) $\frac{2\mathrm{\pi mq}}{\mathrm{B}}$ (b) $\frac{2{\mathrm{\pi q}}^{2}B}{\mathrm{m}}$ (c) $\frac{2\mathrm{\pi qB}}{\mathrm{m}}$ (d) $\frac{2\mathrm{\pi m}}{\mathrm{Bq}}$
8.
At each of the two ends of a rod of length 2r, a particle of mass m and charge q is attached. If this rod is rotated about its centre with angular speed ω, the ratio of its magnetic dipole moment to the total angular momentum of this particle is _____ .
 (a) $\frac{q}{2\mathrm{m}}$ (b) $\frac{q}{\mathrm{m}}$ (c) $\frac{2q}{\mathrm{m}}$ (d) $\frac{q}{\mathrm{\pi m}}$
9.
A very long solenoid of length L has n layers. There are N turns in each layer. Diameter of the solenoid is D and it carries current I. The magnetic field at the centre of the solenoid is _____ .
 (a) directly proportional to D (b) inversely proportional to D. (c) independent of D (d) directly proportional to L.
10.
The angular speed of the charged particle is independent of _____ .
 (a) its mass (b) its linear speed (c) charge of particle (d) magnetic field.
Showing 1 to 10 out of 123 Questions