Confusion regarding eddy current losses
Eddy losses is a component of core losses. It essentially occurs when there's a change in the magnetic field of said core. We engineers would perform eddy-current testing to see and measure these "cracks" within the core to determine how much eddy current there is.

When we detect some flaws, heat will be generated. This means that there will be kinetic energy that will convert into thermal energy. This is known as eddy losses.

The textbook equation for eddy losses is 
\$ P_e=K_eB_m^2t^2f^2V\$ watts.

Eddy losses depend on frequency, thus you will get a different value when you have 50Hz and 100kHz.

Someone in the comments mentioned the Skin Effect. This is a phenomenon where at high frequencies, the magnetic field will not be able to penetrate the inside of the core. The equation I mentioned a few lines higher is only true if you disregard the Skin Effect. HOWEVER, if you keep the same magnetic field with increasing frequency, it will in fact increase the eddy current generated.