Q. No.If a charge '\(q\)' moves with velocity \(v\), in a region where electric field (\(E\)) and magnetic field (\(B\)) both exist, then force on it is:
1. \(q(\vec{v} \times \vec{B})\)
2. \(q \vec{E}+{q}(\vec{v} \times \vec{B})\)
3. \( q \vec{E}+q(\vec{B} \times \vec{v})\)
4. \(q\vec{B}+{q}(\vec{E} \times \vec{v})\)
1. \( 3\times 10^{-4}~\text{N}\)
2. \(3\sqrt2\times10^{-5}~\text{N}\)
3. \(3\times10^3~\text{N}\)
4. zero
A proton carrying 1 MeV kinetic energy is moving in a circular path of radius R in a uniform magnetic field. What should be the energy of an -particle to describe a circle of the same radius in the same field?
1. 2 MeV 2. 1 MeV
3. 0.5 MeV 4. 4 MeV
1. \(3\)
2. \(6\)
3. \(12\)
4. \(2\)
| 1. | a magnet |
| 2. | an unmagnetised iron bar |
| 3. | a moving charge |
| 4. | stationary charge |
What is the magnitude of magnetic force per unit length on a wire carrying a current of \(8~\text{A}\) and making an angle of \(30^{\circ}\) with the direction of a uniform magnetic field of \(0.15~\text{T}?\)
| 1. | \(0.04~\text{N/m}\) | 2. | \(0.6~\text{N/m}\) |
| 3. | \(1.5~\text{N/m}\) | 4. | \(0.33~\text{N/m}\) |
| 1. | \(ILB\) | 2. | \(ILB\cos30^\circ\) |
| 3. | \(ILB\sin30^\circ\) | 4. | \(ILB\tan30^\circ\) |
A uniform electric field and a uniform magnetic field are acting in the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron :
1. speed will decrease
2. speed will increase
3. will turn towards the left of the direction of motion
4. will turn towards right of direction a motion
| Column-I | Column-II | ||
| A. | A charged particle is moving in uniform electric and magnetic fields in gravity free space | P. | The velocity of the particle may be constant |
| B. | A charged particle is moving in uniform electric, magnetic, and gravitational fields | Q. | The path of the particle may be a straight line |
| C. | A charged particle is moving in uniform magnetic and gravitational fields (where the electric field is zero) | R. | The path of the particle may be circular |
| D. | A charged particle is moving in only a uniform electric field | S. | The path of the particle may be helical |
| A | B | C | D | |
| 1. | P, Q, S | P, Q, R, S | P, Q, S | Q |
| 2. | P, Q, R | S, P, Q | P | R, S |
| 3. | P, R | R, P, S | S, R, P | R, P |
| 4. | P, Q, R | S, S | Q, P | R, S |
(rest mass of a proton \(=1.6 \times 10^{-27}~\text{kg}\))
1. \(0.71 ~\text{mT}\)
2. \(7.1 ~\text{mT}\)
3. \(0.071 ~\text{mT}\)
4. \(71 ~\text{mT}\)
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