A coil having \(n\) turns and resistance \(R~\Omega\) is connected with a galvanometer of resistance \(4R~\Omega\). This combination is moved in time \(t\) seconds from a magnetic field \(W_1\) weber/m² to \(W_2\) weber/m². The induced current in the circuit is:
(Assume area = \(1\) m²)

1.	\(-\dfrac{(W_2-W_1)}{5Rnt}\)	2.	\(-\dfrac{n(W_2-W_1)}{5Rt}\)
3.	\(-\dfrac{(W_2-W_1)}{Rnt}\)	4.	\(-\dfrac{n(W_2-W_1)}{Rt}\)

A rectangular coil ABCD is rotated anticlockwise with a uniform angular velocity about the axis shown in the diagram below. The axis of rotation of the coil as well as the magnetic field B are horizontal. The induced e.m.f. in the coil would be maximum when 

1. The plane of the coil is horizontal

2. The plane of the coil makes an angle of 45° with the magnetic field

3. The plane of the coil is at right angles to the magnetic field

4. The plane of the coil makes an angle of 30° with the magnetic field

An electric potential difference will be induced between the ends of the conductor shown in the diagram when the conductor moves in the direction 

1. P

2. Q

3. L

4. M

Two rails of a railway track insulated from each other and the ground are connected to a milli voltmeter. What is the reading of voltmeter, when a train travels with a speed of \(180\) km/hr along the track.
(Given that the vertical component of earth's magnetic field is \(0.2\times 10^{-4}\) weber/m² and the rails are separated by \(1\) m) 
1. \(10^{-2}\) V
2. \(10^{-4}\) V
3. \(10^{-3}\) V
4. \(1\) V

A conducting square loop of side \(L\) and resistance \(R\) moves in its plane with a uniform velocity \(v\) perpendicular to one of its sides. A magnetic induction \(B\) constant in time and space, pointing perpendicular and into the plane of the loop exists everywhere. The current induced in the loop is:

A conducting wire is moving towards right in a magnetic field B. The direction of induced current in the wire is shown in the figure. The direction of magnetic field will be 

1. In the plane of paper pointing towards right

2. In the plane of paper pointing towards left

3. Perpendicular to the plane of paper and down wards

4. Perpendicular to the plane of paper and upwards

One conducting U tube can slide inside another as shown in figure, maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed v then the emf induced in the circuit in terms of B, l and v where l is the width of each tube, will be 

1. Zero

2. 2 Blv

3. Blv

4. – Blv

The magnitude of the earth’s magnetic field at a place is B₀ and the angle of dip is δ. A horizontal conductor of length l lying along the magnetic north-south moves eastwards with a velocity v. The emf induced across the conductor is 

1. Zero

2. B₀lv sinδ

3. B₀lv

4. B₀lv cosδ

Two circuits have coefficient of mutual induction of 0.09 henry. Average e.m.f. induced in the secondary by a change of current from 0 to 20 ampere in 0.006 second in the primary will be 

1. 120 V

2. 80 V

3. 200 V

4. 300 V

A coil and a bulb are connected in series with a dc source, a soft iron core is then inserted in the coil. Then 

1. Intensity of the bulb remains the same

2. Intensity of the bulb decreases

3. Intensity of the bulb increases

4. The bulb ceases to glow