Question is wrong , Air gap flux density , if we are talking about density of flux , why that need to be small??? . smaller or lower flux density means less power will be transfered  . Air gap is kept low , not air gap density , air gap density should be as high as possible . thats why even in transformer we optimised  for higher fluxes till it reach saturation . complete nonsense copying objective and literally no one has solution , all copy paste even answers  . 

The purpose of keeping the air gap flux density low in an induction motor is to improve efficiency.


An induction motor is a type of AC motor widely used in various industrial applications. It operates on the principle of electromagnetic induction, where a rotating magnetic field is produced by the stator windings, which induces current in the rotor windings, causing the rotor to rotate.


The air gap flux density refers to the magnetic flux density in the air gap between the stator and rotor of the motor. It plays a crucial role in determining the motor's performance characteristics, such as efficiency, power factor, and cost.


Efficiency is an important factor in motor design as it determines the amount of electrical energy converted into mechanical energy. By keeping the air gap flux density low, the motor's efficiency can be improved. Here's how:

1. Reduced Iron Losses: Low air gap flux density implies a lower magnetic field strength in the air gap. This results in reduced iron losses, which are caused by hysteresis and eddy current losses in the motor's iron core. Lower iron losses lead to improved efficiency.

2. Minimized Windage and Friction Losses: The air gap flux density also affects the windage and friction losses in the motor. These losses occur due to the movement of air and mechanical friction between the rotating rotor and stationary parts. By keeping the air gap flux density low, the windage and friction losses can be minimized, thereby improving efficiency.

3. Reduced Copper Losses: In an induction motor, the rotor windings carry current induced by the stator's rotating magnetic field. By keeping the air gap flux density low, the induced rotor current can be reduced, resulting in lower copper losses in the rotor. This further contributes to improved efficiency.


In conclusion, the air gap flux density is kept low in an induction motor to improve efficiency. By reducing iron losses, minimizing windage and friction losses, and lowering copper losses, the motor's overall efficiency can be enhanced. This is crucial in achieving energy savings and reducing operating costs in various industrial applications.