Electrical Interview Questions: Electrical Machines (Set 2)

1.Electrical Question: Explain the principle of operation of Electrical Generator?

Answer: When a moving conductor either cut across the lines of stationary magnetic field or when the moving or dynamic magnetic field cuts the stationary conductor then an emf is induced in the conductors. In the first case where the moving conductor cuts the stationary magnetic field, DC Generator works on this principle. In the second case where magnetic field is  dynamic and the conductors are stationary, magnetic field cuts the stationary conductors still emf is induced in this process, large Synchronous Generators and Alternators works on this principle. This emf is induced in both cases by Faraday Electro Magnetic Induction principle.

2.Electrical Question: Explain the Principle of Operation of Electric Motor?

Answer: When a current carrying conductor is placed in a magnetic field in such a way that a component of length of the conductor is perpendicular to the magnetic field, a mechanical force is experienced between the conductors and the magnetic field.

3.Electrical Question: Explain Fleming's Left Hand Rule?

Answer: Fleming's Left hand rule explains the direction in which torque acts on the current carrying conductor in the presence of magnetic field for Electrical Motor.

• ForeFinger of the left hand represents the direction of the magnetic field applied.
• Middle Finger represents the current direction in a conductor
• Thumb of the left hand represents the resultant direction in which torque or motion of force is produce to rotate the motor

4.Electrical Question: Explain Fleming's Right Hand Rule?

Answer: Fleming's Right hand rule explains the direction in which induced current is produced for a moving conductor in the presence of a magnetic field.

• Thumb of the right hand represents the direction of motion of the conductor
• ForeFinger represents the direction of the magnetic field applied
• Middle finger represents the direction in which induced current is produced.

Tip: Thus Fleming's Left hand rule is used to explain the direction of torque or motion produced for Motor. Fleming's Right hand rule is used to explain the direction in which induced current is produced for Generator.

For Remembering this, just remember Fleming's RiGht rule for Generator. Observe the G in right hand and starting letter of G in generator. So simply remember the G for Right and Generator. No confusion...!