Question

What causes the rotating motion in the motor?

Answer 1

Answer:

A coil of wire carrying a current in a magnetic field experiences a force that tends to make it rotate. This effect can be used to make an electric motor

Answer 2

Magnetic Force causes the rotating motion in the motor.

Basic Principle:

• A conductor of length l carrying current i, when kept in an external magnetic field B experiences a magnetic force on it.
• Mathematically, the magnetic force F = i ( l X B)
• The magnetic force experienced by the conductor is maximum when B is perpendicular to l.
• This magnetic force exerts a torque that causes the coil to rotate.

Working:

• A current-carrying coil PQRS is placed between magnets producing a uniform magnetic field B such that B is perpendicular to PQ and RS.
• If current flows from P to Q then the arm PQ experiences a force that rotates it in the clockwise direction.
• Fleming's Left-Hand Rule determines the direction of magnetic force.