From Range of New Stoves Use Magnetic Energy, Not Flames or Coils:
Induction burners tend to cook food faster than traditional stovetops, and advocates of the technology point out that kitchen cleanup is simpler since the glass top can easily be wiped down. But convenience comes at a price. Not only do induction cooktops cost up to twice as much as regular cooktops, but they also work only with pots and pans that have magnetic qualities — no aluminum or Pyrex. Stylish and expensive copper-bottom pans are no good with induction cooktops, either. (The test: If a magnet won’t stick to it, the pan won’t work.)
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The induction devices work like this: Electricity passes through magnetic coils in the cooktop, producing a rapidly fluctuating magnetic field above the burner. That magnetic field forces the molecules in a metal pot to rapidly vibrate — generating friction that heats the pot and ultimately, the food.
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Manufacturers estimate that only 50% or so of the heat generated through electric coils or gas flames on stoves actually gets into the pan to heat up food, the rest of the heat is released into the room. Induction burners, by contrast, are about 90% efficient, manufacturers say.