The current in a coil varies with time t as . If the inductance of coil be 10 mH, the value of induced e.m.f. at \(t=2~\mathrm{s}\) will be:
1. \(0.14~\mathrm{V}\)
2. \(0.12~\mathrm{V}\)
3. \(0.11~\mathrm{V}\)
4. \(0.13~\mathrm{V}\)
A coil having an area is placed in a magnetic field which changes from in time interval t. The average EMF induced in the coil will be:
1.
2.
3.
4.
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
The number of turns in a coil of wire of fixed radius & length is 600 and its self-inductance is 108 mH. The self-inductance of a coil of 500 turns will be:
1. 74 mH
2. 75 mH
3. 76 mH
4. 77 mH
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 coil of resistance 20 and inductance 5 H has been connected to a 200 V battery. The maximum energy stored in the coil is:
1. | 250 J | 2. | 125 J |
3. | 500 J | 4. | 100 J |
An aluminium ring B faces an electromagnet A. If the current I through A can be altered, then:
1. | whether I increases or decreases, B will not experience any force. |
2. | if I decreases, A will repel B. |
3. | if I increases, A will attract B. |
4. | if I increases, A will repel B. |
In the figure magnetic energy stored in the coil is:
1. | Zero | 2. | Infinite |
3. | 25 joules | 4. | None of the above |
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. |