Frequency and Magnetic Field

[Mookie]

Increased / decreased current to a coil / electromagnet has a
direct proportional affect on the strength of the magnetic field.

What about frequency ? 

In North America, household current is delivered at 60 Hz, in Europe at 50 Hz.

What direct affect does higher / lower frequency have on the magnetic field of a coil / electromagnet ?

Mookie

[exnihiloest]

...
What direct affect does higher / lower frequency have on the magnetic field of a coil / electromagnet ?
...

From an electrical viewpoint:
A magnetic field through a circuit induces an emf proportional to dphi/dt which is the rate of the varying magnetic flux, it follows that higher the frequency, higher the voltage emf. There is no consequence on the energy, except for practical considerations about coupling, impedances, losses...

From a physics viewpoint:
Energy density in a magnetic field is B²/(2*µ). It depends only on the field intensity squared, not on the frequency.
The frequency F determines only the energy quanta E=h*F (h= Planck's constant) building the field,  i.e. photons (EM waves) or virtual photons (static and near fields). Therefore same energy density at lower frequency implies only more photons/virtual photons than at higher frequency.