Magnetic field lines are shown in the given diagram. $A$ student makes a statement that the magnetic field at $X$ is stronger than at $Y$. Justify this statement. Also,redraw the diagram and mark the direction of magnetic field lines.

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.

State the observation made by Oersted on the basis of his experiment with current carrying conductors.

List the properties of magnetic field lines.

Choose the incorrect statement from the following regarding magnetic field lines.

State the principle of an electric generator.