The term "squirrel cage" refers to the rotor of a squirrel cage induction motor, which looks like a cage made of conductive bars arranged in a circular pattern. The name is thought to come from the similarity in appearance between the rotor and a cage used to house pet squirrels.
The conductive bars in the rotor are usually made of copper or aluminum, and they are connected at the ends by shorting rings. The rotor is mounted on a shaft that rotates within the stator, and it is typically made of laminated iron or steel. When an AC voltage is applied to the stator, the magnetic field it generates cuts through the rotor, inducing an electric current in the conductive bars. The current flowing through the bars creates its own magnetic field, which interacts with the stator field to produce a force on the rotor and cause it to rotate.
Squirrel cage induction motors are known for their simplicity, reliability, and low cost, and they are widely used in a variety of applications. They are commonly found in fans, pumps, conveyor belts, and other industrial and domestic equipment. They are also used in electric vehicles, such as electric cars and electric bikes.