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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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 |
77%
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Figure shows a metal rod PQ resting on the smooth rails AB and positioned between the poles of a permanent magnet. The rails, the rod, and the magnetic field are in three mutually perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed-loop containing the rod = 9.0 mΩ. Assume the field to be uniform.

What is the magnitude of the induced emf if we will keep the K open and the rod is moved with the speed of 12 cm/s in the direction shown in the figure?

1. 9.8 mV
2. 4.9 mV
3. 0.9 mV
4. 9.0 mV

Subtopic:  Motional emf |
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Figure shows a metal rod PQ resting on the smooth rails AB and positioned between the poles of a permanent magnet. The rails, the rod, and the magnetic field are in three mutually perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed-loop containing the rod = 9.0 mΩ. Assume the field to be uniform.

What is the emf induced in the moving rod if the direction of the magnetic field is changed from perpendicular to parallel to the rails?

1. 0
2. 9 mV
3. 0.9 mV
4. None of these

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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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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