aluminium
cast iron
chrome steel
copper
Answer is Wrong!
Answer is Right!
The correct answer is: A. aluminium
A hysteresis motor is a type of electric motor that uses hysteresis to store energy. The rotor of a hysteresis motor is made of a ferromagnetic material, such as aluminium, that is magnetized by an external magnetic field. The rotor then rotates in the direction of the magnetic field.
The other options are incorrect because they are not ferromagnetic materials. Cast iron is a non-magnetic material, while chrome steel and copper are weakly magnetic materials.
Aluminium is a good choice for the rotor of a hysteresis motor because it is lightweight, has good electrical conductivity, and is relatively inexpensive.