Why the core of a transformer made of a magnetic material of high permeability?

Explanation

When alternating current passes through the primary, the iron core of the transformer gets magnetised and demagnetised over a complete cycly. Thus, some energy is wasted in this process. This is called hysteresis loss ans is proportional to the area of hysteresis loop. Therefore, for reducing this loss of energy, core of the transformer is made of the material whose hysteresis loop is narrow.