The magnetic flux linked with a coil varies with time as \(\phi = 2t^2-6t+5,\) where \(\phi \) is in Weber and \(t\) is in seconds. The induced current is zero at:

1. \(t=0\) 2. \(t= 1.5~\text{s}\)
3. \(t=3~\text{s}\) 4. \(t=5~\text{s}\)

Subtopic:  Faraday's Law & Lenz Law |
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The net magnetic flux through any closed surface, kept in uniform magnetic field is:

1. zero 2. \(\dfrac{\mu_{0}}{4 \pi}\)
3. \(4\pi μ_{0}\) 4. \(\dfrac{4\mu_{0}}{\pi}\)
Subtopic:  Magnetic Flux |
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Level 1: 80%+
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If a current is passed through a circular loop of radius \(R\) then magnetic flux through a coplanar square loop of side \(l\) as shown in the figure \((l<<R)\) is:

          
1. \(\dfrac{\mu_{0} I}{2} \dfrac{R^{2}}{l}\)
2. \(\dfrac{\mu_{0} I l^{2}}{2 R}\)
3. \(\dfrac{\mu_{0}I \pi R^{2}}{2 l}\)
4. \(\dfrac{\mu_{0} \pi R^{2} I}{l}\)

Subtopic:  Magnetic Flux |
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Level 1: 80%+
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The dimensions of inductance are:

1. [MLT-2A-2]
2. [ML2T-2A2]
3. [ML2T-2A-1]
4. [ML2T-2A-2]

Subtopic:  Self - Inductance |
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Level 2: 60%+
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The radius of a loop as shown in the figure is \(10~\text{cm}.\) If the magnetic field is uniform and has a value \(10^{-2}~ \text{T},\) then the flux through the loop will be:
            
1. \(2 \pi \times 10^{-2}~\text{Wb}\)
2. \(3 \pi \times 10^{-4}~\text{Wb}\)
3. \(5 \pi \times 10^{-5}~\text{Wb}\)
4. \(5 \pi \times 10^{-4}~\text{Wb}\)

Subtopic:  Magnetic Flux |
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Level 2: 60%+
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):

Assertion (A): Self-inductance is called the inertia of electricity.
Reason (R): It is on account of self-inductance that the coil opposes any change in current passing through it. 
In the light of the above statements choose the correct answer from the options given below:
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. Both (A) and (R) are False.
Subtopic:  Self - Inductance |
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Given below are two statements: 

Assertion (A): When a piece of non-metal and a metal are dropped from the same height near the surface of the earth, the non-metallic piece will reach the ground first.
Reason (R): Induced current in metal will decrease the acceleration.
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. Both (A) and (R) are False.
Subtopic:  Motional emf |
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Level 1: 80%+
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A short magnet is allowed to fall along the axis of a horizontal metallic ring. Starting from rest, the distance fallen by the magnet in one second may be:

1. \(4\) m 2. \(5\) m
3. \(6\) m 4. \(7\) m
Subtopic:  Motional emf |
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Eddy currents are used in:

1. Induction furnace

2. Electromagnetic brakes

3. Speedometers

4. All of these

Subtopic:  Eddy Current |
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The current through a choke coil increases from zero to \(6\) A in \(0.3\) seconds and an induced emf of \(30\) V is produced. The inductance of the coil is:
1. \(5\) H 2. \(2.5\) H
3. \(1.5\) H 4. \(2\) H
Subtopic:  Self - Inductance |
 91%
Level 1: 80%+
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