An electric generator is a device that converts electrical energy into mechanical energy.

What constitutes the field of a magnet?

The figure shows a long solenoid,a cylindrical coil of a number of turns of insulated copper wire,connected to a battery through an ammeter $A$ and a rheostat $Rh$.
$(i)$ Which end of the solenoid is a $N$-pole and which end is a $S$-pole?
$(ii)$ Draw the magnetic field lines inside the solenoid and indicate their directions. Are magnetic field lines closed?
$(iii)$ How can you increase the strength of the magnetic field inside the solenoid? Give two methods.

The phenomenon of electromagnetic induction is:

The magnitude of an $AC$ voltage used in India is $......$ and its frequency is $......$.

What are the factors on which the magnetic field due to a current carrying solenoid depends?