Smooth cooktops come with any of the three following types of heating elements. Radiant elements are basically electric coils below a ceramic glass top. For efficient heating, they require the use of flat-bottomed pots and pans with bases of the same diameter as the element. Since the coils themselves can t be seen, an indicator light is usually provided to signal a hot surface. They heat up faster than solid disk elements, though not as quickly as conventional coil elements.
Radiant elements are more energy efficient than coil or solid elements.
They use halogen lamps under a glass surface as a heat source. These elements deliver instant heat and respond quickly to changes in the temperature setting. They require flat-bottomed pans for maximum heating efficiency. Magnetic-induction elements are available on some models. These are the most expensive of the three, and heat pots or pans directly, via magnetic induction, instead of heating the cooktop surface.