Question

What is the working principle of an electrical motor? Describe clearly its construction and working method with the help of a diagram.

Hint:

To maintain continuous motion, the commutator in an electric motor reverses the direction of current flow in the armature at regular intervals.

Answer 1

Working Principle of an Electrical Motor:
An electric motor works on the principle of electromagnetic induction. According to this principle, when a current-carrying conductor is placed in a magnetic field, it experiences a force. This force acts on the conductor and causes it to move. The direction of the force is given by the Fleming’s Left-hand Rule, which states that if the forefinger, middle finger, and thumb of the left hand are held perpendicular to each other, the forefinger represents the direction of the magnetic field, the middle finger represents the direction of current, and the thumb represents the direction of motion (force).
Construction of an Electrical Motor:
1. Armature (Rotor): The armature is the rotating part of the motor, usually a coil of wire wound on a laminated iron core.
2. Stator: The stator is the stationary part of the motor that contains the magnets (either permanent magnets or electromagnets) to produce the magnetic field.
3. Commutator: The commutator is a split ring that reverses the direction of current flow in the armature windings to maintain continuous rotation.
4. Brushes: Brushes are carbon or graphite pieces that maintain electrical contact between the rotating armature and the stationary commutator.
5. Power Supply: The motor is connected to an external power supply to provide current to the armature.
Working Method of an Electrical Motor:
1. When current flows through the armature coil, it creates a magnetic field around it.
2. The magnetic field of the armature interacts with the magnetic field of the stator, producing a force that causes the armature to rotate.
3. The direction of the current in the armature is reversed by the commutator at each half-turn to ensure continuous rotation.
Conclusion:
Thus, an electrical motor converts electrical energy into mechanical energy based on the principle of electromagnetic induction.