Class 10, Science, Chapter-12, Lecture-2, Electric Motor (Notes)
EXPERIMENT to demonstrate the force due to magnetic field on a current carrying conductor:
Procedure–
Aluminium rod AB is suspended horizontally with the help of connecting wires.
A strong horseshoe magnet is placed such that the rod lies between the two poles and the field is directed upwards.
Observation–
When current flows through the aluminium rod, it gets displaced.
The direction of displacement of rod changes with change in direction of current.
Conclusion –
- A magnet exerts force on a current-carrying conductor.
- There is a relationship between the direction of magnetic field, the direction of current and the direction of force.
FLEMING’S LEFT HAND RULE:
If the thumb, forefinger, and the central finger of the left hand are stretched mutually perpendicular to each other and if the forefinger points in the direction of the field and the central finger in the direction of the current, then the thumb will point towards the direction of motion of the conductor.
ELECTRIC MOTOR:
A device that converts electric energy to mechanical energy is termed as an electric motor.
WORKING PRINCIPLE OF ELECTRIC MOTOR:
The two opposite arms of a coil experience force in opposite direction, according to Fleming’s Left Hand Rule, when current flows through it in the presence of magnetic field. This causes rotation of the coil.
ALTERNATING CURRENT (AC):
The electric current that changes its direction after certain fixed intervals of time is called alternating current.
AC GENERATOR:
A device that works on the principle of electromagnetic induction and converts mechanical energy to alternating current is called an AC generator.
DIRECT CURRENT (DC):
The electric current that always flows in the same direction is called direct current.
DC GENERATOR:
A device that works on the principle of electromagnetic induction and converts mechanical energy to direct current is called a DC generator.
DIFFERENCES BETWEEN:
Alternating Current (AC) | Direct Current (DC) |
---|---|
1. Flow of current changes direction | 1. Current flows in the same direction |
2. AC can be transmitted over long distances without much loss of energy | 2. DC cannot be transmitted over long distances |