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How does an induction cooktop heat a pan?
A coil beneath the glass creates a rapidly changing magnetic field. In suitable cookware, that field induces electrical currents; electrical resistance dissipates their energy as heat directly in the pan.
What is actually changing?
The useful effect comes from a chain of energy conversions. Looking at each step separately prevents the device from seeming mysterious and makes it easier to compare with other everyday technologies.
Why materials matter
The result depends on material properties: electrical conductivity, magnetic behaviour, molecular structure or semiconductor band structure. Choosing the material is therefore part of the mechanism, not just packaging.
What you can observe
Heat, movement, light or sound is the final visible effect. The intermediate electrical or electromagnetic process may be invisible, but it can be inferred from how the device responds.
Energy does not disappear
The device transforms energy. Some becomes the desired output and some inevitably becomes heat or other losses, which is why efficiency matters.
A useful way to read the diagram
Start at the input, then ask what physical interaction occurs inside the device, and finally identify the output. This input → mechanism → output pattern is reusable across many objects and makes it easier to separate the scientific principle from the engineering details.
Look at the mechanism, not just the object
A useful way to understand an everyday object is to follow a chain: what enters the system, which material or component responds, what physical or chemical change occurs, and what useful effect comes out. This separates the scientific principle from the casing and design.
The same principle often appears in very different objects. Once the mechanism is recognised, links between chemistry, materials, electricity, heat and mechanics become much easier to see.
The coil creates changing magnetic flux
Power electronics drive the coil with alternating current. The time-varying field couples strongly to conductive cookware placed close above it.
The pan becomes the secondary electrical load
Induced eddy currents circulate through the base. Electrical resistance dissipates their energy as heat; ferromagnetic materials can add hysteretic losses depending on operating conditions.
Cookware compatibility is about coupling, not simply “metal”
Copper and aluminium conduct well but couple differently to common cooktops unless designed with a ferromagnetic layer. A magnet sticking to the base is a practical compatibility clue, not the fundamental definition.
Why can the glass remain cooler than a conventional electric hob at first?
Most electrical energy is deposited in the cookware; the glass is then heated mainly by contact with the hot pan.
Common traps to avoid
- The magnetic field is not itself heat.
- Not every electrically conductive pan couples efficiently to a standard induction hob.