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:  Lorentz Force |
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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:  Lorentz Force |
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NEET - 2022
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A particle of mass \(m\) and 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. \(B = {mg \over qv}\)
2. \(B \leq \frac{m g}{q v}\)
3. \(B \geq \frac{m g}{q v}\)
4. \(B = {qv \over mg}\)
Subtopic:  Lorentz Force |
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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:  Lorentz Force |
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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
Subtopic:  Lorentz Force |
 75%
From NCERT
NEET - 2023
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A wire carrying a current \(I_o\) oriented along the vector \(\big(3\widehat{i}+4\widehat{j}\big)\) experiences a force per unit length of \(\big(4F\widehat{i}-3F\widehat{j}-F\widehat{k}\big)\). The magnetic field \(\overrightarrow{B}\) equals:

1. \(\frac{F}{I_o}\big(\widehat{i}+\widehat{j}\big)\)

2. \(\frac{5F}{I_o}\big(\widehat{i}+\widehat{j}+\widehat{k}\big)\)

3. \(\frac{F}{I_o}\big(\widehat{i}+\widehat{j}+\widehat{k}\big)\)

4. \(\frac{5F}{I_o}\widehat{k}\)

Subtopic:  Lorentz Force |
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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:  Lorentz Force |
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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.  \(\frac{\lambda Br}{r}\)
3.  \(\frac{\lambda}{Br}\)
4.  \(\frac{\lambda}{B^2r^2}\)
Subtopic:  Lorentz Force |
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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
Subtopic:  Lorentz Force |
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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 \(I(dl)\) 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:  Biot-Savart Law |
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From NCERT
NEET - 2022
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