A metallic rod of mass per unit length of \(0.5\) kgm–1 is lying horizontally on a smooth inclined plane which makes an angle of \(30^\circ\) with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction of \(0.25\) T is acting on it in the vertical direction. What is the current flowing through the rod to keep it stationary?
1. \(7.14\) A 2. \(5.98\) A
3. \(14.76\) A 4. \(11.32\) A
Subtopic:  Lorentz Force |
 57%
From NCERT
NEET - 2018
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The current sensitivity of a moving coil galvanometer is \(5~\text{div/mA}\) and its voltage sensitivity (angular deflection per unit voltage applied) is \(20~\text{div/V}.\) The resistance of the galvanometer is: 
1. \(40~\Omega\)
2. \(25~\Omega\)
3. \(250~\Omega\)
4. \(500~\Omega\)

Subtopic:  Moving Coil Galvanometer |
 70%
From NCERT
NEET - 2018
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A \(250\) turn rectangular coil of length \(2.1\) cm and width \(1.25\) cm carries a current of \(85~\mu\text{A}\) and subjected to the magnetic field of strength \(0.85~\text{T}\). Work done for rotating the coil by \(180^\circ\) against the torque is:
1. \(4.55~\mu\text{J} \)
2. \(2.3~\mu\text{J} \)
3. \(1.15~\mu\text{J} \)
4. \(9.4~\mu\text{J} \)

Subtopic:  Current Carrying Loop: Force & Torque |
 52%
From NCERT
NEET - 2017
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An arrangement of three parallel straight wires placed perpendicular to the plane of paper carrying the same current in the same direction is shown in the figure. The magnitude of force per unit length on the middle wire \(B\) is given by:
    

1. \(\dfrac{\mu_0i^2}{2\pi d}\) 2. \(\dfrac{2\mu_0i^2}{\pi d}\)
3. \(\dfrac{\sqrt{2}\mu_0i^2}{\pi d}\) 4. \(\dfrac{\mu_0i^2}{\sqrt{2}\pi d}\)
Subtopic:  Force between Current Carrying Wires |
 63%
From NCERT
NEET - 2017
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An electron is moving in a circular path under the influence of a transverse magnetic field of 3.57×10-2 T. If the value of e/m is 1.76×1011 C/kg, the frequency of revolution of the electron is

(1) 1 GHz             

(2) 100 MHz

(3) 62.8 MHz         

(4) 6.28 MHz

Subtopic:  Lorentz Force |
 64%
From NCERT
NEET - 2016
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A square loop ABCD carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current I, the net force on the loop will be:

           

1. μ0Ii2π              2. 2μ0IiL3π

3. μ0IiL2π            4. 2μ0Ii3π

Subtopic:  Current Carrying Loop: Force & Torque |
 56%
From NCERT
NEET - 2016
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A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is \(B\). It is then bent into a circular coil of \(n\) turns. The magnetic field at the centre of this coil of \(n\) turns will be:

1. \(nB\) 2. \(n^2B\)
3. \(2nB\) 4. \(2n^2B\)
Subtopic:  Magnetic Field due to various cases |
 84%
From NCERT
NEET - 2016
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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 |
 67%
From NCERT
NEET - 2016
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If a square loop \(\text{ABCD}\) carrying a current \(i\) is placed near and coplanar with a long straight conductor \(\mathrm{XY}\) carrying a current \(I,\) what will be the net force on the loop?
                 
1. \(\frac{\mu_0Ii}{2\pi}\)
2. \(\frac{2\mu_0IiL}{3\pi}\)
3. \(\frac{\mu_0IiL}{2\pi}\)
4. \(\frac{2\mu_0Ii}{3\pi}\)

Subtopic:  Current Carrying Loop: Force & Torque |
 63%
From NCERT
NEET - 2016
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A long straight wire of radius a carries a steady current \(I\). The current is uniformly distributed over its cross-section. The ratio of the magnetic fields \(B\) and \(B'\) at radial distances \(\frac{a}{2}\) and \(2a\) respectively, from the axis of the wire, is:
1. \(\frac{1}{2}\)
2. \(1\)
3. \(4\)
4. \(\frac{1}{4}\)
Subtopic:  Ampere Circuital Law |
 62%
From NCERT
NEET - 2016
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