What's the difference between Frequency and Amperage?

You mentioned Frequency equates to amplitude or strength of the magnetic field into the part. What effect does controlling amperage have?

Frequency of operation determines how deep the induced electric currents will penetrate your metal workpiece. Higher the operating frequency the higher is the amount of heat produced and shallower is the depth its produced in. Amperage of the coil determines the strength of the magnetic field. The higher the amperage, the higher is the magnetic field. Amperage does not affect the depth of the induced eddy currents in the metal workpiece.