Heating by electromagnetic induction involves placing the material or product in a fluctuating magnetic field. Heat may be applied directly to the product, which heats it from inside, or indirectly to a surrounding cover made of metal or other material, heating it by induction. For more information, see Section 4.6.4 of the page New Energy Efficient Technologies That Are Applicable to Manufacturing Processes on the Natural Resources Canada Web site.
Ohmic heating, also known as Joule and resistive heating, is a process whereby electric current is passed directly through an item in order to heat it.
It is suitable for materials that are reasonably good conductors and often difficult to treat (because they are heat-sensitive, very viscous or messy, for instance). It can quickly heat large volumes at very precise power levels.