What is the principle of an electric motor?

$A$ positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is

State the principle of an electric generator.

What precaution should be taken to avoid the overloading of domestic electric circuits?

Why do not two magnetic field lines intersect each other?

State the rule to determine the direction of: $(i)$ a magnetic field produced around a straight current-carrying conductor,$(ii)$ force experienced by a current-carrying straight conductor placed in a magnetic field perpendicular to it,and $(iii)$ current induced in a coil due to its rotation in a magnetic field.