The magnetic flux linked with a coil varies with time as ϕ = 2t2-6t+5, where ϕ is in weber and t is in seconds. The induced current is zero at:

1. t = 0

2. t = 1.5 s

3. t = 3 s

4. t = 5 s

Subtopic:  Faraday's Law & Lenz Law |
 90%
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A coil having number of turns N and cross-sectional area A is rotated in a uniform magnetic field B with an angular velocity ω. The maximum value of the emf induced in it is:

1. NBAω                             

2. NBAω

3. NBAω2                             

4. NBAω2

Subtopic:  Faraday's Law & Lenz Law |
 88%
From NCERT
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The current in a coil varies with time t as I = 3t2+ 2t. If the inductance of coil be 10 mH, the value of induced e.m.f. at \(t=2~\mathrm{s}\) will be:
1. \(0.14~\mathrm{V}\)
2. \(0.12~\mathrm{V}\)
3. \(0.11~\mathrm{V}\)
4. \(0.13~\mathrm{V}\)

Subtopic:  Faraday's Law & Lenz Law |
 88%
From NCERT
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In a circuit with a coil of resistance 2 ohms, the magnetic flux changes from 2.0 Wb to 10.0 Wb in 0.2 second. The charge that flows in the coil during this time is:
1. 5.0 coulomb
2. 4.0 coulomb
3. 1.0 coulomb
4. 0.8 coulomb

Subtopic:  Faraday's Law & Lenz Law |
 88%
From NCERT
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A bar magnet is released along the vertical axis of the conducting coil. The acceleration of the bar magnet is:

1. greater than g. 2. less than g.
3. equal to g. 4. zero.
Subtopic:  Faraday's Law & Lenz Law |
 85%
From NCERT
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A coil having an area A0 is placed in a magnetic field which changes from B0 to 4B0 in time interval t. The average EMF induced in the coil will be:

1. 3A0B0t

2. 4A0B0t

3. 3B0A0t

4. 4B0A0t

Subtopic:  Faraday's Law & Lenz Law |
 87%
From NCERT
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A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. 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 |
 73%
From NCERT
AIPMT - 2013
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An aluminium ring B faces an electromagnet A. If the current I through A can be altered, then:

1. whether I increases or decreases, B will not experience any force.
2. if I decreases, A will repel B.
3. if I increases, A will attract B.
4. if I increases, A will repel B.
Subtopic:  Faraday's Law & Lenz Law |
 70%
From NCERT
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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 e.m.f. in the loop when the radius is 2 cm is:

1. \(3.2\pi ~\mu V\)

2. \(4.8\pi ~\mu V\)

3. \(0.8\pi ~\mu V\)

4. \(1.6\pi ~\mu V\)

Subtopic:  Faraday's Law & Lenz Law |
 69%
From NCERT
AIPMT - 2009
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A magnet is brought towards a coil first (i) speedily (ii) slowly. It can be concluded that the induced e.m.f. and the induced charge in the two cases, will be respectively:

1. More in the first case, more in the first case.
2. More in the first case, equal in both cases.
3. Less in the first case, more in the second case.
4. Less in the first case, equal in both cases.


 

Subtopic:  Faraday's Law & Lenz Law |
 68%
From NCERT
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