A particle of mass \(m,\) charge \(Q,\) and kinetic energy \(T\) enters a transverse uniform magnetic field of induction \(\vec B.\) What will be the kinetic energy of the particle after seconds?

1. \(3{T}\) 2. \(2{T}\)
3. \({T}\) 4. \(4{T}\)
Subtopic:  Lorentz Force |
 86%
Level 1: 80%+
AIPMT - 2008
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What is the result of an electric charge in uniform motion?

1. an electric field only.
2. a magnetic field only.
3. both electric and magnetic field.
4. neither electric nor magnetic field.

Subtopic:  Lorentz Force |
 82%
Level 1: 80%+
PMT - 1971
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The magnetic force acting on a charged particle of charge \(-2~\mu\text{C}\) in a magnetic field of \(2\) T acting in the \(y\text-\)direction, when the particle velocity is \((2\hat{i}+3\hat{j})\times10^6 ~\text{ms}^{-1}\) is:
1. \(8\) N in \(-z\text-\)direction.
2. \(4\) N in the \(z\text-\)direction.
3. \(8\) N in the \(y\text-\)direction.
4. \(8\) N in the \(z\text-\)direction.
Subtopic:  Lorentz Force |
 72%
Level 2: 60%+
AIPMT - 2009
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A particle of charge \(+q\) and mass \(m\) moving under the influence of a uniform electric field \(E\hat i\) and a uniform magnetic field \(\mathrm B\hat k\) follows a trajectory from \(P\) to \(Q\) as shown in the figure. The velocities at \(P\) and \(Q\) are \(v\hat i\) and \(-2v\hat j\) respectively. Which of the following statement(s) is/are correct?

       
1. \(E=\frac{3}{4} \frac{{mv}^2}{{qa}}\).
2. Rate of work done by electric field at \(P\) is \(\frac{3}{4} \frac{{mv}^3}{a}\).
3. Rate of work done by both fields at \(Q\) is zero.
4. All of the above.
Subtopic:  Lorentz Force |
 71%
Level 2: 60%+
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Moving perpendicular to field \(B\), a proton and an alpha particle both enter an area of uniform magnetic field \(B\). If the kinetic energy of the proton is \(1~\text{MeV}\) and the radius of the circular orbits for both particles is equal, the energy of the alpha particle will be:
1. \(4~\text{MeV}\)
2. \(0.5~\text{MeV}\)
3. \(1.5~\text{MeV}\)
4. \(1~\text{MeV}\)

Subtopic:  Lorentz Force |
 72%
Level 2: 60%+
NEET - 2015
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A beam of electrons passes un-deflected through mutually perpendicular electric and magnetic fields. Where do the electrons move if the electric field is switched off and the same magnetic field is maintained?

1. in an elliptical orbit.
2. in a circular orbit.
3. along a parabolic path.
4. along a straight line.

Subtopic:  Lorentz Force |
 72%
Level 2: 60%+
AIPMT - 2007
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A current-carrying wire is placed in a uniform magnetic field in the shape of the curve \(y= \alpha \sin \left({\pi x \over L}\right),~0 \le x \le2L.\) 
What will be the force acting on the wire?
                   

1. \(iBL \over \pi\) 2. \(iBL \pi\)
3. \(2iBL \) 4. zero
Subtopic:  Lorentz Force |
 70%
Level 2: 60%+
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An electron is moving in a circular path under the influence of a transverse magnetic field of \(3.57\times 10^{-2}~\text{T}\). If the value of \(\frac{e}{m}\) is \(1.76\times 10^{11}~\text{C/kg}\), what will be the frequency of revolution of the electron?
1. \(1~\text{GHz}\) 2. \(100~\text{MHz}\)
3. \(62.8~\text{MHz}\) 4. \(6.28~\text{MHz}\)
Subtopic:  Lorentz Force |
 68%
Level 2: 60%+
NEET - 2016
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A particle with charge \(q\), moving with a momentum \(p\), enters a uniform magnetic field normally. The magnetic field has magnitude \(B\) and is confined to a region of width \(d\), where \(d< \frac{p}{Bq}.\) The particle is deflected by an angle \(\theta\) in crossing the field, then:

       

1.  \(\sin \theta=\frac{Bqd}{p}\) 2. \(\sin \theta=\frac{p}{Bqd}\)
3. \(\sin \theta=\frac{Bp}{qd}\) 4. \(\sin \theta=\frac{pd}{Bq}\)
Subtopic:  Lorentz Force |
 67%
Level 2: 60%+
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When a charged particle with velocity \(\vec v\) is subjected to an induction magnetic field \(\vec B,\) the force on it is non-zero. What does this imply?
1. Angle between \(\vec v\) and \(\vec {B}\) is necessarily \(90^{\circ}\).
2. Angle between \(\vec v\) and \(\vec {B}\) can have any value other than \(90^{\circ}\).
3. Angle between \(\vec v\) and \(\vec {B}\) can have any value other than zero and \(180^{\circ}\).
4. Angle between \(\vec v\) and \(\vec {B}\) is either zero or \(180^{\circ}\).
Subtopic:  Lorentz Force |
 70%
Level 2: 60%+
AIPMT - 2006
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