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Q. No.Given below are two statements:
| Statement I: | A charged particle moving in a magnetic field experiences a force which is zero only when it moves in the direction of the field or against it. |
| Statement II: | Whenever a charged particle moves in a uniform magnetic field, its trajectory may be a circle, a straight line or a helix. |
| 1. | Statement I is incorrect and Statement II is correct. |
| 2. | Both Statement I and Statement II are correct. |
| 3. | Both Statement I and Statement II are incorrect. |
| 4. | Statement I is correct and Statement II is incorrect. |
Subtopic: Â Lorentz Force |
 73%
Level 2: 60%+
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A strong magnetic field is applied along the direction of the velocity of an electron. The electron would move along:
| 1. | a parabolic path |
| 2. | the original path |
| 3. | a helical path |
| 4. | a circular path |
Subtopic: Â Lorentz Force |
 67%
Level 2: 60%+
NEET - 2022
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A particle of mass \(m\) and the charge \(q\) is observed to move with a uniform velocity \(v\) in a region containing a uniform magnetic field \(B,\) and a uniform gravitational field \(g.\) The magnetic field \(B\) must satisfy:
1. \(B = \dfrac{mg}{qv}\)
2. \(B \leq \dfrac{m g}{q v}\)
3. \(B \geq \dfrac{m g}{q v}\)
4. \(B = \dfrac{qv}{mg}\)
1. \(B = \dfrac{mg}{qv}\)
2. \(B \leq \dfrac{m g}{q v}\)
3. \(B \geq \dfrac{m g}{q v}\)
4. \(B = \dfrac{qv}{mg}\)
Subtopic: Â Lorentz Force |
Level 3: 35%-60%
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A straight wire of mass \(200~\text{g}\) and length \(1.5~\text{m}\) carries a current of \(2~\text{A}.\) It is suspended in mid-air by a uniform horizontal magnetic field \(B\) (shown in the figure). What is the magnitude of the magnetic field?
| 1. | \(0.65~\text{T}\) | 2. | \(0.77~\text{T}\) |
| 3. | \(0.44~\text{T}\) | 4. | \(0.20~\text{T}\) |
Subtopic: Â Lorentz Force |
 82%
Level 1: 80%+
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A long straight wire of length \(2\) m and mass \(250\) g is suspended horizontally in a uniform horizontal magnetic field of \(0.7\) T. The amount of current flowing through the wire will be:
(\(g=9.8~\text{ms}^{-2}\))
1. \(2.45\) A
2. \(2.25\) A
3. \(2.75\) A
4. \(1.75\) A
(\(g=9.8~\text{ms}^{-2}\))
1. \(2.45\) A
2. \(2.25\) A
3. \(2.75\) A
4. \(1.75\) A
Subtopic: Â Lorentz Force |
 79%
Level 2: 60%+
NEET - 2023
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A wire carrying a current \(I_0\) oriented along the vector \(\big(3\hat{i}+4\hat{j}\big)\) experiences a force per unit length of \(\big(4F\hat{i}-3F\hat{j}-F\hat{k}\big).\) The magnetic field \(\vec{ B}\) equals:
1. \(\dfrac{F}{I_0}\left(\hat{i}+\hat{j}\right)\)
2. \(\dfrac{5F}{I_0}\left(\hat{i}+\hat{j}+\hat{k}\right)\)
3. \(\dfrac{F}{I_0}\left(\hat{i}+\hat{j}+\hat{k}\right)\)
4. \(\dfrac{5F}{I_0}\hat{k}\)
Subtopic: Â Lorentz Force |
Level 3: 35%-60%
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A charged particle moves in a gravity-free space without change in velocity. Which of the following is/are possible?
| a. | \(E=0,~B=0\) |
| b. | \(E=0,~B\neq0\) |
| c. | \(E\neq0,~B=0\) |
| d. | \(E\neq0,~B\neq0\) |
Choose the correct option:
| 1. | (a), (b), (d) |
| 2. | (b), (c), (a) |
| 3. | (c), (d), (b) |
| 4. | (a), (c), (d) |
Subtopic: Â Lorentz Force |
 64%
Level 2: 60%+
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A charged particle moves in a circular path of radius \(r\) in a uniform magnetic field \(B,\) perpendicular to the plane of motion. The same particle is observed to move in a circular path around an infinite line charge \(\lambda\) (charge/unit length), moving with the same kinetic energy as before. The charge to mass ratio of the particle is proportional to:
| 1. | \(\lambda Br\) | 2. | \(\dfrac{\lambda Br}{r}\) |
| 3. | \(\dfrac{\lambda}{Br}\) | 4. | \(\dfrac{\lambda}{B^2r^2}\) |
Subtopic: Â Lorentz Force |
Level 3: 35%-60%
Hints
Two particles of equal mass \(m\) and charge \(q\) move in a circular orbit of radius \(r\) under the influence of a magnetic field \(B.\) The kinetic energy of the particles is proportional to (assume that the particles don't exert electrostatic forces on each other):
1. \(q^{2}\)
2. \(B^{2}\)
3. \(r^{2}\)
4. All of the above
1. \(q^{2}\)
2. \(B^{2}\)
3. \(r^{2}\)
4. All of the above
Subtopic: Â Lorentz Force |
 90%
Level 1: 80%+
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Given below are two statements:
| Statement I: | Biot-Savart's law gives us the expression for the magnetic field strength of an infinitesimal current element \((Idl)\) of a current-carrying conductor only. |
| Statement II: | Biot-Savart's law is analogous to Coulomb's inverse square law of charge \(q,\) with the former being related to the field produced by a scalar source, \((Idl)\) while the latter being produced by a vector source, \(q.\) |
| 1. | Statement I is incorrect but Statement II is correct. |
| 2. | Both Statement I and Statement II are correct. |
| 3. | Both Statement I and Statement II are incorrect. |
| 4. | Statement I is correct but Statement II is incorrect. |
Subtopic: Â Biot-Savart Law |
 56%
Level 3: 35%-60%
NEET - 2022
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