A power transformer is used to step up an alternating e.m.f. of 220 V to 11 kV to transmit 4.4 kW of power. If the primary coil has 1000 turns, what is the current rating of the secondary ? Assume 100% efficiency for the transformer 

1. 4 A

2. 0.4 A

3. 0.04 A

4. 0.2 A

Subtopic:  Transformer |
 76%
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The primary winding of transformer has 500 turns whereas its secondary has 5000 turns. The primary is connected to an ac supply of 20 V, 50 Hz. The secondary will have an output of 

1. 200 V, 50 Hz

2. 2 V, 50 Hz

3. 200 V, 500 Hz

4. 2 V, 5 Hz

Subtopic:  Transformer |
 81%
From NCERT
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A step-down transformer is connected to main supply 200V to operate a 6V, 30W bulb. The current in primary is 

1. 3 A

2. 1.5 A

3. 0.3 A

4. 0.15 A

Subtopic:  Transformer |
 77%
From NCERT
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Two conducting circular loops of radii \(R_1\) and \(R_2\) are placed in the same plane with their centres coinciding. If \(R_1>>R_2\), the mutual inductance \(M\) between them will be directly proportional to:

1. \(\dfrac{R_1}{R_2}\) 2. \(\dfrac{R_2}{R_1}\)
3. \(\dfrac{R^2_1}{R_2}\) 4. \(\dfrac{R^2_2}{R_1}\)
Subtopic:  Mutual Inductance |
 63%
From NCERT
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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 |
 68%
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A circular loop of radius R carrying current I lies in the x-y plane with its centre at the origin. The total magnetic flux through the x-y plane is 

1. Directly proportional to I

2. Directly proportional to R

3. Directly proportional to R2

4. Zero

Subtopic:  Magnetic Flux |
 53%
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A small square loop of wire of side l is placed inside a large square loop of wire of side L (L > l). The loop are coplanar and their centre coincide. The mutual inductance of the system is proportional to 

1. l / L

2. l2 / L

3. L/l

4. L2/l

Subtopic:  Mutual Inductance |
 79%
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A uniform but time-varying magnetic field B(t) exists in a circular region of radius a and is directed into the plane of the paper, as shown. The magnitude of the induced electric field at point P at a distance r from the centre of the circular region 

1. Is zero

2. Decreases as 1r

3. Increases as r

4. Decreases as 1r2

Subtopic:  Faraday's Law & Lenz Law |
 59%
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Two circular coils can be arranged in any of the three situations shown in the figure. Their mutual inductance will be 

1. Maximum in situation (A)

2. Maximum in situation (B)

3. Maximum in situation (C)

4. The same in all situations

Subtopic:  Mutual Inductance |
 74%
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A conducting rod of length 2l is rotating with constant angular speed ω about its perpendicular bisector. A uniform magnetic field B exists parallel to the axis of rotation. The e.m.f. induced between two ends of the rod is 

1. BΩl2

2. 12Bωl2

3. 18Bωl2

4. Zero

Subtopic:  Motional emf |
 57%
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