Q. No.What is the dimensional formula of magnetic flux?
1. \(\left[ M L^2 T^{-2}A^{-1}\right]\)
2. \(\left[ M L^1 T^{-1}A^{-2}\right]\)
3. \(\left[ M L^2 T^{-3}A^{-1}\right]\)
4. \(\left[ M L^{-2} T^{-2}A^{-2}\right]\)
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. |
| 1. | \(5000\) V | 2. | \(500\) V |
| 3. | \(150\) V | 4. | \(125\) V |
The direction of the induced current \(I\) in the figure is:
| 1. | From \(a\) to \(b\) and from \(c\) to \(d\) |
| 2. | From \(a\) to \(b\) and from \(f\) to \(e\) |
| 3. | From \(b\) to \(a\) and from \(d\) to \(c\) |
| 4. | From \(b\) to \(a\) and from \(e\) to \(f\) |
A pair of adjacent coils has a mutual inductance of \(1.5~\text H.\) If the current in one coil changes from \(0\) to \(20~\text A\) in \(0.5~\text s,\) what is the change of flux linkage with the other coil?
| 1. | \(35~\text{Wb}\) | 2. | \(25~\text{Wb}\) |
| 3. | \(30~\text{Wb}\) | 4. | \(20~\text{Wb}\) |
Current in a circuit falls from \(5.0~\text A\) to \(0~\text A\) in \(0.1~\text{s}\). If an average emf of \(200~\text V\) is induced, the self-inductance of the circuit is:
1. \(4~\text H\)
2. \(2~\text H\)
3. \(1~\text H\)
4. \(3~\text H\)
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. \(150~\text{V}\)
A copper rod of mass \(m\) slides under gravity on two smooth parallel rails \(l\) distance apart and set at an angle \(\theta\) to the horizontal as shown in figure. At the bottom, the rails are joined by a resistance \(R.\) There is a uniform magnetic field perpendicular to the plane of the rails. The terminal velocity of the rod is:
| 1. | \(\dfrac{m g R \cos \theta}{B^{2} l^{2}}\) | 2. | \(\dfrac{m g R \sin \theta}{B^{2} l^{2}}\) |
| 3. | \(\dfrac{m g R \tan \theta}{B^{2} l^{2}}\) | 4. | \(\dfrac{m g R \cot \theta}{B^{2} l^{2}}\) |
A \(10\) H inductor carries a current of \(20\) A. How much ice at \(0^{\circ}\text{C}\) could be melted by the energy stored in the magnetic field of the inductor?
Latent heat of ice is \(2.26\times 10^{3}\) J/kg.
| 1. | \(0.08\) kg | 2. | \(8.8\) kg |
| 3. | \(0.88\) kg | 4. | \(0.44\) kg |
Some magnetic flux is changed from a coil of resistance \(10~\Omega\). As a result, an induced current is developed in it, which varies with time as shown in the figure. The magnitude of change in flux through the coil in Wb is:
| 1. | \(2\) | 2. | \(4\) |
| 3. | \(6\) | 4. | None of these |
© 2026 GoodEd Technologies Pvt. Ltd.