No two magnetic field lines can intersect each other. Explain.

What happens to the deflection of the compass needle placed at a point near a current-carrying straight conductor:
$(a)$ If the current is increased?
$(b)$ If the direction of current in the conductor is changed (reversed)?
$(c)$ If the compass is moved away from the conductor?

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

When an electric current flows through a conducting wire,what is produced in the region around it?

The material of the core of a strong electromagnet is:

Under what condition does a current-carrying conductor kept in a magnetic field experience maximum force? On what other factors does the magnitude of this force depend? Name and state the rule used for the determination of the direction of this force.