<P> Cookware must be compatible with induction heating; in most models, only ferrous metal can be heated . Cookware usually have a flat bottom since the magnetic field drops rapidly with distance from the surface . (Special and costly wok - shaped tops are available for use with round - bottom woks .) Induction disks are metal plates that are heated by induction and heat non-ferrous pots by thermal contact, but these are much less efficient than ferrous cooking vessels . </P> <P> Induction compatible cookware for an induction cooking surface can nearly always be used on other stoves . Some cookware or packaging is marked with symbols to indicate compatibility with induction, gas, or electric heat . Induction cooking surfaces work well with any pans with a high ferrous metal content at the base . Cast iron pans and any black metal or iron pans will work on an induction cooking surface . Stainless steel pans will work on an induction cooking surface if the base of the pan is a magnetic grade of stainless steel . If a magnet sticks well to the sole of the pan, it will work on an induction cooking surface . An "all - metal" cooker will work with non-ferrous cookware, but available models are limited . </P> <P> Aluminum or copper alone does not work on an induction stove because of the materials' magnetic and electrical properties . Aluminum and copper cookware are more conductive than steel, but the skin depth in these materials is larger since they are non-magnetic . The current flows in a thicker layer in the metal, encounters less resistance and so produces less heat . The induction cooker will not work efficiently with such pots . However, aluminum and copper are desirable in cookware, since they conduct heat better . Because of this' tri-ply' pans often have an induction - compatible skin of stainless steel containing a layer of thermally conductive aluminum . </P> <P> For frying, a pan with a base that is a good heat conductor is needed to spread the heat quickly and evenly . The sole of the pan will be either a steel plate pressed into the aluminum, or a layer of stainless steel over the aluminum . The high thermal conductivity of aluminum pans makes the temperature more uniform across the pan . Stainless frying pans with an aluminum base will not have the same temperature at their sides as an aluminum sided pan will have . Cast iron frying pans work well with induction cooking surfaces but the material is not as good a thermal conductor as aluminum . </P>

Which two types of cookware will not work for induction cooking