Question

Explain the construction and working of an electric motor.

Answer 1

Hint:Electric motor uses the principle of magnetic force on a current carrying conductor. The direction of force depends on the direction of current flow and magnetic field. However, we can fix the magnetic field and create torque on a loop depending on the current flow. That is how electric motors are constructed.


Complete step by step solution:
Let’s look at the following diagram to understand the construction of electric motor:

So, we have the following components in an electric motor:

1) Field magnet is either constructed using a pain of permanent magnets or using an electromagnet.
2) Armature is the loop inside the magnetic field which conducts current and experiences the torque.
3) Split Ring Communicator connects the armature and provides mechanical support.
4) Brushes connect the electric supply to the communicator. It is a fixed support for the communicator.

Working principle:
When a charged particle moves through space, it creates a magnetic field. We can assume electric flow through a conductor to be electrons moving through it. So, a magnetic field will be generated due to the conductor interacting with the magnetic field of the permanent magnet. This interaction can either be an attraction or a repulsion.

The direction of magnetic field generated due to the conductor depends on the flow of current. As there are two sides (AB & CD) which are perpendicular to the permanent magnetic field, and the current flow is opposite in them, they will experience equal and opposite force.

Hence, it will create a torque on the armature, and it will start rotating. This is how the armature inside the motor rotates around its axis.

Note: We can also consider the loop to behave like a magnet having its own magnetic moment. We can find the interaction depending on the interaction between the magnetic field due to the whole loop and the magnetic field of the permanent magnet.