As the title say, this is what my text book say. I use Hughes Electrical Electronic Technology 10th edition
The varying flux in the core induces e.m.f.s and hence currents in the core material. These give rise to \$I^2R\$ losses. These losses are called eddy-current losses
However then when I search through the internet
I found this and it says
Copper loss is I2R loss, in primary side it is \$I_1^2R_1\$ and in secondary side it is \$I_2^2R_2\$ loss, where \$I_1\$ & \$I_2\$ are primary & secondary current of transformer and \$R_1\$ & \$R_2\$ are resistances of primary & secondary winding. As the both primary & secondary currents depend upon load of transformer, copper loss in transformer vary with load.
Hysteresis loss and eddy current loss, both depend upon magnetic properties of the materials used to construct the core of transformer and its design. So these losses in transformer are fixed and do not depend upon the load current
They are kinda contradict each other. So, what's the right definition for copper loss and eddy-current loss