The EMF generated in a moving rod within a uniform magnetic field \(B\) is \(0.08~\text{V}.\) The speed \((v)\) of the rod is:
1. \(1\) m/s 2. \(2\) m/s
3. \(3\) m/s 4. \(4\) m/s

Subtopic: Β Motional emf |
Β 92%
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In given L-R circuit connected with a D.C source of 12V, inductance is LmH and resistances is 6 Ω. If the emf induced in the inductor at t = 1mS is 10V, value of L is:

1. \({{3}\over{\ln\left({1.2}\right)}}\)
2. \({{6}\over{\ln\left({1.2}\right)}}\)
3. \({{3}\over{\ln\left({1.8}\right)}}\)
4. \({{6}\over{\ln\left({2.4}\right)}}\)
Subtopic: Β LR circuit |
Β 62%
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Consider the following Assertion and Reason:
Assertion (A): Moving magnet in conducting pipe slows down.
Reason (R): Because eddy current is formed.
 
1. (A) is correct but (R) is wrong.
2. Both (A) and (R) are wrong.
3. Both (A) and (R) are correct.
4. (A) is wrong but (R) is correct.
Subtopic: Β Eddy Current |
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A cube with side length \(25~\text{cm}\) is moving with a uniform velocity of \(8~\text{m/s}\) in the positive \(y\)-direction, as shown in the figure. The cube is placed in a uniform magnetic field of \(1~\text{T},\) which is directed along the negative \(z\)-axis. The magnitude of the induced EMF across the opposite faces of the cube is:
1. \(2~\text{V}\) 2. \(4~\text{V}\)
3. \(8~\text{V}\) 4. \(6~\text{V}\)
Subtopic: Β Motional emf |
Β 74%
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Variation of the magnetic field through a coil of area \(4 ~\text m^2\) is shown in the figure. What is the emf induced in the coil (in mV)? 
      
1. \(8 ~\text{mV}\)
2. \(16~\text{mV}\)
3. \(4 ~\text{mV}\)
4. \(2 ~\text{mV}\)
Subtopic: Β Faraday's Law & Lenz Law |
Β 77%
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A circular ring is placed in a magnetic field of \(0.4\) T. Suddenly its radius starts shrinking at the rate of \(1\) mm/s. What will be the induced EMF in the ring at \(r = 2~\text{cm?}\) 
1. \(16 \pi~\mu \text{V}\)
2. \(8 \pi~\mu \text{V}\)
3. \(16 \pi~ \text{mV}\)
4. \(8 \pi~ \text{mV}\)
Subtopic: Β Magnetic Flux |
Β 66%
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A circular loop of radius \(\dfrac{10}{\sqrt{\pi}}\) cm is placed in a linearly varying perpendicular magnetic field which has magnitude \(0.5\) T at time \(t=0.\) The magnetic field reduces to zero at \(t=0.5~\text{s}\). The emf induced in the loop at \(t=0.25~\text{s}\) is:
(where \(r\) is the radius of the circular loop)
1. \(0.01~\text{V}\) 2. \(0.005~\text{V}\)
3. \(0.02~\text{V}\) 4. \(0.03~\text{V}\)
Subtopic: Β Faraday's Law & Lenz Law |
From NCERT
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In a part of the circuit, as shown, it is given that the current is decreasing at a rate of \(1~\text{A/s}.\) Then \(V_A-V_B\) is equal to:
      
1. \(18~\text{V}\)
2. \(-18~\text{V}\)
3. \(9~\text{V}\)
4. \(-9~\text{V}\)
Subtopic: Β LR circuit |
Β 80%
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The magnetic field through a circular loop is \(0.8\) T. The radius of the loop is expanding at the rate of \(2\) cm/s. The induced emf in the loop, when the radius of the loop is \(10\) cm is:
1. \(32\times 10^{-4}\) V
2. \(16\times 10^{-4}\) V
3. \(32\times 10^{-2}\) V
4. \(16\times 10^{-2}\) V
Subtopic: Β Faraday's Law & Lenz Law |
Β 74%
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A small circular loop of radius \(r\) is placed in the plane of a square loop of side length \(L\) \((r \ll L).\) A circular loop is at the center of the square as shown in the figure. The mutual inductance of the given system is:
1. \({\dfrac{\mu_{0}r^{2}}{\sqrt{2}L}}\) 2. \({\dfrac{\pi\mu_{0}r^{2}}{2L}}\)
3. \({\dfrac{2\sqrt{2}\mu_{0}r^{2}}{L}}\) 4. \({\dfrac{4\mu_{0}r^{2}}{L}}\)
Subtopic: Β Mutual Inductance |
Β 67%
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