Q. No.An electron enters a chamber in which a uniform magnetic field is present as shown.
An electric field of appropriate magnitude is also applied so that the electron travels undeviated without any change in its speed through the chamber. We are ignoring gravity. Then, the direction of the electric field is:
| 1. | opposite to the direction of the magnetic field. |
| 2. | opposite to the direction of the electron's motion. |
| 3. | normal to the plane of the paper and coming out of the plane of the paper. |
| 4. | normal to the plane of the paper and into the plane of the paper. |
An electric current \(i\) enters and leaves a uniform circular wire of radius \(a\) through diametrically opposite points. A charged particle \(q\) moving along the axis of the circular wire passes through its centre at speed \(v\). The magnetic force acting on the particle when it passes through the centre has a magnitude:
1. \(qv\dfrac{\mu_{0} {i}}{2 {a}}m\)
2. \(qv\dfrac{\mu_{0} {i}}{2 {\pi a}}\)
3. \(qv\dfrac{\mu_{0}{i}}{ {a}}\)
4. zero
Which of the following particles will experience maximum magnetic force (magnitude) when projected with the same velocity perpendicular to a magnetic field?
1. electron
2. proton
3. \(\text{He}^{+}\)
4. \(\text{Li}^{++}\)
A charged particle moves along a circle under the action of possible constant electric and magnetic fields. Which of the following are possible?
| (a) | \(E=0, ~B=0\) |
| (b) | \(E=0, ~B\ne0\) |
| (c) | \(E\ne0, ~B=0\) |
| (d) | \(E\ne0, ~B\ne0\) |
Choose the correct option:
1. (a), (b)
2. (b) only
3. (c), (d)
4. (a), (d)
If a charged particle at rest experiences no electromagnetic force then,
| (a) | the electric field must be zero. |
| (b) | the magnetic field must be zero. |
| (c) | the electric field may or may not be zero. |
| (d) | the magnetic field may or may not be zero. |
Choose the correct option:
| 1. | (a), (b) | 2. | (b), (c) |
| 3. | (c), (d) | 4. | (a), (d) |
A cubical region of space is filled with some uniform electric and magnetic fields. An electron enters the cube across one of its faces with velocity \(v\) and a positron enters via the opposite face with velocity \(-v\). At this instant,
| (a) | the electric forces on both the particles cause identical accelerations. |
| (b) | the magnetic forces on both the particles cause equal accelerations. |
| (c) | both particles gain or lose energy at the same rate. |
| (d) | the motion of the centre of mass (CM) is determined by \(\vec{B}\) alone. |
Choose the correct option:
1. (a), (b), (c)
2. (a), (c), (d)
3. (b), (c), (d)
4. (c), (d)
A charged particle would continue to move with a constant velocity in a region wherein,
| 1. | \(E=0, ~B\ne0\) |
| 2. | \(E\ne0, ~B\ne0\) |
| 3. | \(E\ne0, ~B=0\) |
| 4. | \(E=0, ~B=0\) |
Choose the correct option:
1. (a), (c)
2. (b), (d)
3. (b), (c), (d)
4. (c), (d)
1. \(3\)
2. \(6\)
3. \(12\)
4. \(2\)
In a region of space, magnetic field is parallel to the positive \(y\text-\)axis and the charged particle is moving along the positive \(x\text-\)axis (as shown in the figure). The directions of Lorentz force for an electron (negative charge) and proton (positive charge) are respectively:
| 1. | \(-z\text-\)axis, \(+z\text-\)axis | 2. | \(+z\text-\)axis, \(-z\text-\)axis |
| 3. | \(-z\text-\)axis, \(-z\text-\)axis | 4. | \(+z\text-\)axis, \(+z\text-\)axis |
1. \(1\)
2. \(4\)
3. \(2\)
4. \(0\)
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