# A $$1~\text{m}$$ long metallic rod is rotating with an angular frequency of $$400~\text{rad/s}$$ about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of $$0.5~\text{T}$$ parallel to the axis exists everywhere. The emf induced between the centre and the ring is: 1. $$200~\text{V}$$ 2. $$100~\text{V}$$ 3. $$50~\text{V}$$ 4. $$150~\text{V}$$

Subtopic:  Motional emf |
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A circular coil of radius 8.0 cm and 20 turns is rotated about its vertical diameter with an angular speed of 50 rad/s in a uniform horizontal magnetic field of magnitude  The maximum emf induced in the coil is:

1. 0.603 V
2. 0.01 V
3. 0
4. 1 V

Subtopic:  Motional emf |
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A horizontal straight wire $$10$$ m long extending from east to west is falling with a speed of $$5.0$$ ms-1 at right angle to the horizontal component of the earth's magnetic field, $$0.30 \times 10^{-4} ~\text{Wb m}^{-2}$$. The instantaneous value of the emf induced in the wire is:
 1 $$2.5 \times 10^{-3} ~\text V$$ 2 $$1.5 \times 10^{-4} ~\text V$$ 3 $$2.5 \times 10^{-4}~\text V$$ 4 $$1.5 \times 10^{-3} ~\text V$$
Subtopic:  Motional emf |
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Current in a circuit falls from $$5.0$$ A to $$0$$ A in $$0.1~\text{s}$$. If an average emf of $$200$$ V is induced, the self-inductance of the circuit is:
1. $$4$$ H
2. $$2$$ H
3. $$1$$ H
4. $$3$$ H

Subtopic:  Self - Inductance |
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A rectangular wire loop of sides $$8$$ cm and $$2$$ cm with a small cut is moving out of a region of the uniform magnetic field of magnitude $$0.3$$ T directed normal to the loop. What is the EMF developed across the cut if the velocity of the loop is $$1$$ cm/s in a direction normal to the longer side?
1. $$2.4 \times10^{-4}~\text V$$
2. $$2.0 \times10^{-3}~\text V$$
3. $$1.3 \times10^{-4}~\text V$$
4. $$1.7 \times10^{-3}~\text V$$

Subtopic:  Motional emf |
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A jet plane is traveling towards the west at a speed of $$1800$$ km/h. What is the voltage difference developed between the ends of the wing having a span of $$25$$ m, if the Earth’s magnetic field at the location has a magnitude of $$5\times 10^{-4}~\text{T}$$ and the dip angle is $$30^{\circ}$$.
1. $$2.712~\text{V}$$
2. $$3.125~\text{V}$$
3. $$1.112~\text{V}$$
4. $$3.011~\text{V}$$

Subtopic:  Motional emf |
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A pair of adjacent coils has a mutual inductance of $$1.5$$ H. If the current in one coil changes from $$0$$ to $$20$$ A in $$0.5$$ s, what is the change of flux linkage with the other coil?

 1 $$35$$ Wb 2 $$25$$ Wb 3 $$30$$ Wb 4 $$20$$ Wb
Subtopic:  Mutual Inductance |
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If a loop changes from an irregular shape to a circular shape, then magnetic flux linked with it:

1. Decreases

2. Remains constant

3. First decreases and then increases

4. Increases

Subtopic:  Magnetic Flux |
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A line charge λ per unit length is lodged uniformly onto the rim of a wheel of mass M and radius R. The wheel has light non-conducting spokes and is free to rotate without friction about its axis (as shown in the figure). A uniform magnetic field extends over a circular region within the rim. It is given by,

What is the angular velocity of the wheel after the field is suddenly switched off?

1. $$-\frac{2 \pi B_0 a^2 \lambda}{M R} \hat{k}$$
2. $$-\frac{\pi B_0 a^2 \lambda}{M R} \hat{k}$$
3. $$-\frac{2 B_0 a^2 \lambda}{M R} \hat{k}$$
4. $$-\frac{2 B_0 a^2 \lambda}{\pi M R} \hat{k}$$

Subtopic:  Motional emf |
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A straight wire carries a current of 50 A and the loop is moved to the right with a constant velocity, v= 10 m/s. the induced emf in the loop at the instant when x = 0.2 m, is:
(Take a = 0.1 m and assume that the loop has a large resistance.)

1.$$3.4 \times10^{-5} V$$
2.$$1.7 \times10^{-5} V$$
3.$$1.7 \times10^{-4} V$$
4.$$3.4 \times10^{-4} V$$

Subtopic:  Motional emf |
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