To understand the basics of Electrical Engineering one must understand the difference between a purely resistive load and a purely inductive load.

A inductive load has no resistive or capacitive component in it.So the power factor will also be never unity.As a result the power consumed by a inductive load for same current capacity with respect to a resistve load will be greater than the latter.

In this youtube video https://youtube.com/watch?v=WlF_Cn-zjO0 you will understand how a purely inductive load is varied by moving the iron core using a soft iron handle.

As we apply the mains ac supply to the inductive load, the ac is passed through the copper windings which generates a magnetic field.This magnetic field is strong enough to oppose the force being exerted to remove the iron core from the magnetic field.The force applied is directly proportional to the ac supply being applied from the Variac.In conclusion the more centrally aligned core of the inuctive load the more is the current being produced as you can see from the video.

In this video itself you will be able to understand calculation of power and power factor