A uniform magnetic field is restricted within a region of radius \(r\). The magnetic field changes with time at a  rate \(\frac{dB}{dt}\). Loop \(1\) of radius \(R>r\) is enclosed within the region \(r\) and loop \(2\) of radius \(R\) is outside the region of the magnetic field as shown in the figure. Then, the emf generated is:
           

1. zero in loop \(1\) and zero in loop \(2\)
2. \(-\frac{dB}{dt}\pi r^2\) in loop \(1\) and zero in loop \(2\)
3.  \(-\frac{dB}{dt}\pi R^2\) in loop \(1\) and zero in loop \(2\)
4. zero in loop \(1\) and not defined in loop \(2\)

Subtopic:  Faraday's Law & Lenz Law |
 69%
From NCERT
NEET - 2016
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A long solenoid has \(1000\) turns. When a current of \(4~\text{A}\) flows through it, the magnetic flux linked with each turn of the solenoid is \(4\times 10^{-3}~\text{Wb}\). The self-inductance of the solenoid is:
1. \(3~\text{H}\)
2. \(2~\text{H}\)
3. \(1~\text{H}\)
4. \(4~\text{H}\)
Subtopic:  Self - Inductance |
 88%
From NCERT
NEET - 2016
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An electron moves on a straight-line path \(XY\) as shown. The \(\mathrm{abcd}\) is a coil adjacent to the path of electrons. What will be the direction of current if any, induced in the coil? 
  

1. \(\mathrm{abcd}\)
2. \(\mathrm{adcb}\)
3. The current will reverse its direction as the electron goes past the coil
4. No current included

Subtopic:  Faraday's Law & Lenz Law |
 75%
From NCERT
NEET - 2015
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A conducting square frame of side \(a\) and a long straight wire carrying current \(I\) are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity \(v.\) The emf induced in the frame will be proportional to:


     
1. \( \frac{1}{x^2} \)
2. \( \frac{1}{(2 x-a)^2} \)
3. \( \frac{1}{(2 x+a)^2} \)
4. \(\frac{1}{(2 x-a)(2 x+a)}\)

Subtopic:  Motional emf |
 72%
From NCERT
NEET - 2015
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A coil of self-inductance \(L\) is connected in series with a bulb \(B\) and an AC source. The brightness of the bulb decreases when:
1. number of turns in the coil is reduced.
2. a capacitance of reactance \(X_C = X_L\) is included in the same circuit.
3. an iron rod is inserted in the coil.
4. frequency of the AC source is decreased.
Subtopic:  Self - Inductance |
 67%
From NCERT
AIPMT - 2013
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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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The current \(i\) in a coil varies with time as shown in the figure. The variation of induced emf with time would be:
     

1.   2.
3. 4.
Subtopic:  Faraday's Law & Lenz Law |
 69%
From NCERT
AIPMT - 2011
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A conducting circular loop is placed in a uniform magnetic field of \(0.04\) T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at a rate of \(2\) mm/s. The induced emf in the loop when the radius is \(2\) cm is:
1. \(3.2\pi ~\mu \text{V}\)

2. \(4.8\pi ~\mu\text{V}\)

3. \(0.8\pi ~\mu \text{V}\)

4. \(1.6\pi ~\mu \text{V}\)

Subtopic:  Faraday's Law & Lenz Law |
 70%
From NCERT
AIPMT - 2009
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A rectangular, a square, a circular, and an elliptical loop, all in the \((x\text-y)\) plane, are moving out of a uniform magnetic field with a constant velocity, \(\vec{v}= v\hat{i}.\) The magnetic field is directed along the negative \(z\text-\)axis direction. The induced emf, during the passage of these loops out of the field region, will not remain constant for:
1. the rectangular, circular, and elliptical loops.
2. the circular and the elliptical loops.
3. only the elliptical loop.
4. any of the four loops.
Subtopic:  Motional emf |
 72%
From NCERT
AIPMT - 2009
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A circular disc of radius \(0.2~\text{m}\) is placed in a uniform magnetic field of induction \(\frac{1}{\pi}~\text{Wb/m}^{2}\) in such a way that its axis makes an angle of \(60^{\circ}\) with \(\vec{B}.\) The magnetic flux linked with the disc is:
1. \(0.02~\text{Wb}\)
2. \(0.06~\text{Wb}\)
3. \(0.08~\text{Wb}\)
4. \(0.01~\text{Wb}\)
Subtopic:  Magnetic Flux |
 85%
From NCERT
AIPMT - 2008
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