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 |
 87%
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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 |
 88%
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An electric potential difference will be induced between the ends of the conductor shown in the diagram when the conductor moves in the direction of:

    

1. P
2. Q
3. L
4. M

Subtopic:  Motional emf |
 70%
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The number of turns in a coil of wire of fixed radius & length is 600 and its self-inductance is 108 mH. The self-inductance of a coil of 500 turns will be:

1.  74 mH

2.  75 mH

3.  76 mH

4.  77 mH

Subtopic:  Self - Inductance |
 78%
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An aeroplane in which the distance between the tips of wings is 50 m is flying horizontally with a speed of 360 km/hr over a place where the vertical component of earth magnetic field is 2.0×10-4 weber/m2. The potential difference between the tips of wings would be:

1. 0.1 V  2. 1.0 V
3. 0.2 V  4. 0.01 V
Subtopic:  Motional emf |
 81%
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A magnetic rod is inside a coil of wire which is connected to an ammeter. If the rod is stationary, which of the following statements is true?

1. The rod induces a small current.
2. The rod loses its magnetic field.
3. There is no induced current.
4. None of these.

Subtopic:  Motional emf |
 80%
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A coil of resistance 20 Ω and inductance 5 H has been connected to a 200 V battery. The maximum energy stored in the coil is:

1. 250 J 2. 125 J
3. 500 J 4. 100 J
Subtopic:  Self - Inductance |
 86%
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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 |
 69%
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In the figure magnetic energy stored in the coil is:

1. Zero 2. Infinite
3. 25 joules 4. None of the above
Subtopic:  LR circuit |
 83%
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Consider the situation shown in the figure. The wire AB is sliding on the fixed rails with a constant velocity. If the wire AB is replaced by semicircular wire, the magnitude of the induced current will:

   

1. increase.
2. remain the same.
3. decrease.
4. increase or decrease depending on whether the semicircle bulges towards the resistance or away from it.
Subtopic:  Motional emf |
 70%
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