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 |
 70%
From NCERT
NEET - 2015
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A circuit contains an ammeter, a battery of \(30~\text{V}\), and a resistance \(40.8~\Omega\) all connected in series. If the ammeter has a coil of resistance \(480~\Omega\) and a shunt of \(20~\Omega\), then the reading in the ammeter will be:
1. \(0.5~\text{A}\)
2. \(0.02~\text{A}\)
3. \(2~\text{A}\)
4. \(1~\text{A}\)

Subtopic:  Conversion to Ammeter & Voltmeter |
 62%
From NCERT
NEET - 2015
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A rectangular coil of length \(0.12~\text{m}\) and width \(0.1~\text{m}\) having \(50\) turns of wire is suspended vertically in a uniform magnetic field of strength \(0.2~\text{Wb/m}^2\). The coil carries a current of \(2~\text{A}\). If the plane of the coil is inclined at an angle of \(30^{\circ}\) with the direction of the field, the torque required to keep the coil in stable equilibrium will be:
1. \(0.15~\text{N-m}\)
2. \(0.20~\text{N-m}\)
3. \(0.24~\text{N-m}\)
4. \(0.12~\text{N-m}\)

Subtopic:  Current Carrying Loop: Force & Torque |
From NCERT
NEET - 2015
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A wire carrying current \(I\) has the shape as shown in the adjoining figure. Linear parts of the wire are very long and parallel to \(X\)-axis while the semicircular portion of radius \(R\) is lying in the \(Y\text-Z\) plane. The magnetic field at point \(O\) is:

   
1. \(B=\frac{\mu i }{4\pi R}\left ( \pi \hat{i}+2\hat{k} \right )\)
2. \(B=-\frac{\mu i }{4\pi R}\left ( \pi \hat{i}-2\hat{k} \right )\)
3. \(B=-\frac{\mu i }{4\pi R}\left ( \pi \hat{i}+2\hat{k} \right )\)
4. \(B=\frac{\mu i }{4\pi R}\left ( \pi \hat{i}-2\hat{k} \right )\)
Subtopic:  Magnetic Field due to various cases |
 66%
From NCERT
NEET - 2015
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An electron moving in a circular orbit of radius \(r\) makes \(n\) rotations per second. The magnetic field produced at the centre has a magnitude:
1. \(\frac{\mu_0ne}{2\pi r}\)
2. zero
3. \(\frac{n^2e}{r}\)
4. \(\frac{\mu_0ne}{2r}\)

Subtopic:  Magnetic Field due to various cases |
 66%
From NCERT
NEET - 2015
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In an ammeter, \(0.2 \%\) of the main current passes through the galvanometer. If the resistance of the galvanometer is \(G,\) the resistance of the ammeter will be:

1. \({1 \over 499}G\) 2. \({499 \over 500}G\)
3. \({1 \over 500}G\) 4. \({500 \over 499}G\)
Subtopic:  Conversion to Ammeter & Voltmeter |
 53%
From NCERT
AIPMT - 2014
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Two identical long conducting wires \(\mathrm{AOB}\) and \(\mathrm{COD}\) are placed at a right angle to each other, with one above the other such that '\(O\)' is the common point for the two. The wires carry \(I_1\) and \(I_2\) currents, respectively. Point '\(P\)' is lying at a distance '\(d\)' from '\(O\)' along a direction perpendicular to the plane containing the wires. What will be the magnetic field at the point \(P\)?

1. \(\dfrac{\mu_0}{2\pi d}\left(\dfrac{I_1}{I_2}\right )\) 2. \(\dfrac{\mu_0}{2\pi d}\left[I_1+I_2\right ]\)
3. \(\dfrac{\mu_0}{2\pi d}\left[I^2_1+I^2_2\right ]\) 4. \(\dfrac{\mu_0}{2\pi d}\sqrt{\left[I^2_1+I^2_2\right ]}\)
Subtopic:  Magnetic Field due to various cases |
 76%
From NCERT
AIPMT - 2014
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A current loop in a magnetic field:
1. can be in equilibrium in one orientation
2. can be in equilibrium in two orientations, both the equilibrium states are unstable
3. can be in equilibrium in two orientations, one stable while the other is unstable
4. experiences a torque whether the field is uniform or non-uniform in all orientations
Subtopic:  Current Carrying Loop: Force & Torque |
 74%
From NCERT
AIPMT - 2013
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When a proton is released from rest in a room, it starts with an initial acceleration \(a_0\) towards the east. When it is projected towards the north with a speed of \(v_0\), it moves with an initial acceleration of \(3a_0\) towards the east. What are the electric and magnetic fields in the room?
1. \(\frac{M a_0}{e} ~\text{west,}~ \frac{M a_0}{e v_0}~\text{up}\)
2. \(\frac{M a_0}{e} ~\text {west,} ~\frac{2 M a_0}{e v_0}~\text{down}\)
3. \(\frac{M a_0}{e} ~\text{east,} \frac{2 M a_0}{e v_0}~\text{up}\)
4. \(\frac{M a_0}{e} ~\text {east,} \frac{3 M a_0}{e v_0} ~\text {down}\)

Subtopic:  Lorentz Force |
 56%
From NCERT
AIPMT - 2013
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A long straight wire carries a certain current and produces a magnetic field \(2 \times 10^{-4} \) Wb/m2 at a perpendicular distance of \(5\) cm from the wire. An electron situated at \(5\) cm from the wire moves with a velocity \(10^7 \) m/s towards the wire along perpendicular to it. The force experienced by the electron will be:
(Charge on electron = \(1.6 \times 10^{-19} \) C)
1. \(3.2\)
2. \(3.2 \times 10^{-16} \) N
3. \(1.6 \times 10^{-16} \) N
4. zero 
Subtopic:  Lorentz Force |
 72%
From NCERT
NEET - 2013
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