The current in a coil varies with time \(t\) as \(I= 3 t^{2} +2t\). If the inductance of coil be \(10\) mH, the value of induced emf at \(t=2~\text{s}\) will be:
1. \(0.14~\text{V}\)
2. \(0.12~\text{V}\)
3. \(0.11~\text{V}\)
4. \(0.13~\text{V}\)
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. |
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. |