Magnetic Effect of Electric Current — Important Questions

Number of turns in the coil, Current through the coil, Material of the core

The magnetic field strength of a solenoid depends on: (1) Number of turns - more turns create stronger field, (2) Current - higher current increases field strength, (3) Core material - soft iron core greatly increases field strength. Wire color has no effect on magnetic properties.

Armature, Split ring commutator, Carbon brushes, Permanent magnets

Main parts of an electric motor: (1) Armature - rotating coil, (2) Split ring commutator - reverses current direction, (3) Carbon brushes - maintain contact with commutator, (4) Permanent magnets - provide magnetic field. Galvanometer is a measuring instrument, not a motor part.

North pole to south pole outside the magnet

Magnetic field lines always flow from north pole to south pole outside the magnet, and from south pole to north pole inside the magnet, forming closed loops. The direction is defined by the direction a north pole would move if placed in the field.

Into the coil (south pole)

When current flows clockwise through a coil (when viewed from one end), that end behaves as a south pole and magnetic field lines point into the coil. When current is anticlockwise, that end becomes north pole with field lines pointing out.