Question

State Fleming’s Left-Hand Rule and explain the principle of an electric motor.

Hint:

Fleming’s Left-Hand Rule helps determine the direction of force on a current-carrying conductor in a magnetic field. Electric motors work on the principle that a current-carrying conductor placed in a magnetic field experiences a force.

Answer 1

Concept: An electric motor is a device that converts electrical energy into mechanical energy. The working of an electric motor is based on the principle that a current-carrying conductor placed in a magnetic field experiences a force. The direction of this force is determined using Fleming’s Left-Hand Rule.
Step 1:Fleming’s Left-Hand Rule.
Fleming’s Left-Hand Rule is used to determine the direction of force acting on a current-carrying conductor placed in a magnetic field. The rule states: " If the thumb, forefinger, and middle finger of the left hand are stretched mutually perpendicular to each other, then: "

• The forefinger represents the direction of the magnetic field.
• The middle finger represents the direction of current.
• The thumb represents the direction of the force (or motion) acting on the conductor.

This rule helps in predicting the motion of the conductor in an electric motor.
Step 2:Principle of an Electric Motor.
The electric motor works on the principle that: " A current-carrying conductor placed in a magnetic field experiences a mechanical force. " When electric current flows through a coil placed between the poles of a magnet:

• The magnetic field interacts with the magnetic field produced by the current.
• This interaction produces a force on the sides of the coil.
• The forces act in opposite directions on the two sides of the coil, causing the coil to rotate.

Thus, electrical energy supplied to the coil is converted into mechanical energy in the form of rotational motion.
Step 3:Working of an Electric Motor (Brief).

• A rectangular coil is placed between the poles of a magnet.
• When current passes through the coil, forces act on opposite sides of the coil.
• These forces produce a turning effect that rotates the coil.
• A split-ring commutator reverses the direction of current after every half rotation to maintain continuous motion.

Thus, the electric motor converts electrical energy into mechanical energy using the interaction between magnetic fields and electric current.