A coil of resistance \(400~\Omega\) is placed in a magnetic field. The magnetic flux \(\phi~\text{(Wb)}\) linked with the coil varies with time \(t~\text{(s)}\) as \(\phi=50t^{2}+4.\) The current in the coil at \(t=2~\text{s}\) is:
1. \(0.5~\text{A}\)
2. \(0.1~\text{A}\)
3. \(2~\text{A}\)
4. \(1~\text{A}\)

Subtopic:  Faraday's Law & Lenz Law |
 87%
From NCERT
AIPMT - 2012
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The current (\(I\)) in the inductance is varying with time (\(t\)) according to the plot shown in the figure. 

          
Which one of the following is the correct variation of voltage with time in the coil?
1.   2.
3. 4.
Subtopic:  Self - Inductance |
 73%
From NCERT
AIPMT - 2012
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A conducting circular loop is placed in a uniform magnetic field, \(B=0.025~\text{T}\) with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of \(1~\text{mm s}^{-1}\).  The induced emf, when the radius is \(2~\text{cm}\), is:
1. \(2\pi ~\mu\text{V}\)
2. \(\pi ~\mu\text{V}\)
3. \(\frac{\pi}{2}~\mu\text{V}\)
4. \(2 ~\mu \text{V}\)

Subtopic:  Faraday's Law & Lenz Law |
 75%
From NCERT
AIPMT - 2010
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A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced emf is:
1. twice per revolution.
2. four times per revolution.
3. six times per revolution.
4. once per revolution.
 
Subtopic:  Faraday's Law & Lenz Law |
 74%
From NCERT
AIPMT - 2013
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The magnetic potential energy stored in a certain inductor is \(25\) mJ, when the current in the inductor is \(60\) mA. This inductor is of inductance:
1. \(0.138\) H
2. \(138.88\) H
3. \(1.389\) H
4. \(13.89\) H

Subtopic:  Self - Inductance |
 68%
From NCERT
NEET - 2018
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In a coil of resistance \(10\) \(\Omega\), the induced current developed by changing magnetic flux through it is shown in the figure as a function of time. The magnitude of change in flux through the coil in Weber is:

     

1. \(2\)
2. \(6\)
3. \(4\)
4. \(8\)

Subtopic:  Magnetic Flux |
 67%
From NCERT
AIPMT - 2012
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The figure shows planar loops of different shapes moving out of or into a region of a magnetic field which is directed normally to the plane of the loop away from the reader. Then:

            

1. for the rectangular loop abcd, the induced current is clockwise.
2. for the triangular loop abc, the induced current is clockwise.
3. for the irregularly shaped loop abcd, the induced current is anti-clockwise.
4. none of these.

Subtopic:  Faraday's Law & Lenz Law |
 66%
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A wheel with \(10\) metallic spokes each \(0.5\) m long is rotated with a speed of \(120\) rev/min in a plane normal to the horizontal component of earth’s magnetic field HE at a place. If \(H_E=0.4\) G at the place, what is the induced emf between the axle and the rim of the wheel? (\(1\) G=\(10^{-4}\) T)
1. \(5.12\times10^{-5}\) T
2. \(0\)
3. \(3.33\times10^{-5}\)
4. \(6.28\times10^{-5}\)

Subtopic:  Motional emf |
 64%
From NCERT
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Two concentric circular coils, one of small radius \(\mathrm{r_1}\) and the other of large radius \(\mathrm{r_2},\) such that \(\mathrm{r_1<<r_2},\)  are placed co-axially with centres coinciding. The mutual inductance of the arrangement is:
1. \(\frac{\mu_0\pi r_1^2}{3r_2}\)

2. \(\frac{2\mu_0\pi r_1^2}{r_2}\)
3. \(\frac{\mu_0\pi r_1^2}{r_2}\)
4. \(\frac{\mu_0\pi r_1^2}{2r_2}\)

Subtopic:  Mutual Inductance |
 67%
From NCERT
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The expression for the magnetic energy stored in a solenoid in terms of magnetic field \(B\), area \(A\) and length \(l\) of the solenoid is:
1. \( \frac{1}{\mu_0}B^2Al\)
2. \( \frac{1}{2\mu_0}B^2Al\)
3. \( \frac{2}{\mu_0}B^2Al\)
4. 
\( \frac{3}{2\mu_0}B^2Al\)

Subtopic:  Self - Inductance |
 82%
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