why the no-load power factor of an induction motor / transformer is very low?

The no-load power factor of an induction motor or transformer is very low primarily due to the predominance of reactive power at this operating condition. At no load, the motor or transformer draws only magnetizing current, which is largely reactive and necessary for establishing the magnetic field. This reactive current contributes little to real power, resulting in a low power factor. Consequently, the motor or transformer operates inefficiently under no-load conditions, as most of the power drawn is not used for useful work.