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 |
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. |
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. \(150~\text{V}\)
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 |
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. | \({mgR \over B^2l}\) |
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. |
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. |
An electric potential difference will be induced between the ends of the conductor shown in the diagram when the conductor moves in the direction of:
1. P
2. Q
3. L
4. M
A rod having length l and resistance R0 is moving with speed v as shown in the figure. The current through the rod is:
1.
2.
3.
4.
A thin semicircular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is v and the potential difference developed across the ring is:
1. | Zero |
2. | \(B v \pi R^2 / 2\) and M is at the higher potential |
3. | \(2 R B v\) and M is at the higher potential |
4. | \(2RBv\) and Q is at the higher potential |