Figure shows the current flowing in the coil of wire wound around the soft iron horse shoe core.

(a) State the polarities developed at the ends A and B.

(b) How will the polarity at the ends A and B change on reversing the direction of current.

(c) Suggest one way to increase the strength of magnetic filed produced.

The incomplete diagram of an electric bell is given in figure. Draw winding of coil on the core and complete the electric circuit in the diagram.

The magnitude of force acting on a current carrying wire placed in a magnetic field in a direction perpendicular to its length depends on :

1. The current flowing in the wire
2. The strength of the magnetic field
3. The length of the wire
4. all of the above

The speed of rotation of coil can be increased by :

1. decreasing the strength of the magnetic field
2. decreasing the area of the coil
3. increasing the area of the coil
4. decreasing the number of turns in the coil