Q. No.An aeroplane in which the distance between the tips of wings is 50 m is flying horizontally with a speed of 360 km/hr over a place where the vertical component of earth magnetic field is . The potential difference between the tips of wings would be:
| 1. | 0.1 V | 2. | 1.0 V |
| 3. | 0.2 V | 4. | 0.01 V |
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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, \(0.30 \times 10^{-4} \mathrm{~Wb} \mathrm{~m}^{-2}\)
. The instantaneous value of the emf induced in the wire is:
| 1. | \(2.5 \times 10^{-3} V\) |
| 2. | \(1.5 \times 10^{-4} V\) |
| 3. | \(2.5 \times 10^{-4} V\) |
| 4. | \(1.5 \times 10^{-3} V\) |
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A magnetic rod is inside a coil of wire which is connected to an ammeter. If the rod is stationary, which of the following statements is true?
| 1. | The rod induces a small current. |
| 2. | The rod loses its magnetic field. |
| 3. | There is no induced current. |
| 4. | None of these. |
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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 center and the ring is:
1. \(200~\text{V}\)
2. \(100~\text{V}\)
3. \(50~\text{V}\)
4. \(150~\text{V}\)
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A square metallic wire loop of side 0.1 m and resistance of \(1~\Omega\) is moved with a constant velocity in a magnetic field of \(2~\mathrm{wb/m^2}\) as shown in the figure. The magnetic field is perpendicular to the plane of the loop and the loop is connected to a network of resistances. What should be the velocity of the loop so as to have a steady current of 1 mA in the loop?
| 1. | 1 cm/sec | 2. | 2 cm/sec |
| 3. | 3 cm/sec | 4. | 4 cm/sec |
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A wire cd of length l and mass m is sliding without friction on conducting rails ax and by as shown. The vertical rails are connected to each other with a resistance R between a and b. A uniform magnetic field B is applied perpendicular to the plane abcd such that cd moves with a constant velocity of:
| 1. | \({mgR \over Bl}\) | 2. | \({mgR \over B^2l^2}\) |
| 3. | \({mgR \over B^3l^3}\) | 4. | \({mgR \over B^2l}\) |
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A conductor ABOCD moves along its bisector with a velocity of 1 m/s through a perpendicular magnetic field of \(1~\mathrm{wb/m^2}\), as shown in fig. If all the four sides are of 1 m length each, then the induced emf between points A and D is:
1. 0
2. 1.41 volt
3. 0.71 volt
4. None of the above
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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. |
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A conducting square frame of side 'a' and a long straight wire carrying current i are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity v. The emf induced in the frame will be proportional to:
1. 1/x2
2. 1/(2x-a)2
3. 1/(2x+a)2
4. 1/(2x-a) x (2x+a)
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When a conducting wire XY is moved towards the right, a current flows in the anti-clockwise direction. Direction of magnetic field at point O is:
| 1. | parallel to the motion of wire. |
| 2. | along with XY. |
| 3. | perpendicular outside the paper. |
| 4. | perpendicular inside the paper. |
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