The induction cook tops use electromagnetism to cook food. This force governing both electricity and magnetism is many times stronger than gravity. Electromagnetic induction happens when current flow in one circuit induces current flow in another circuit by simply placing the second circuit near the first one. But how does this happen even without touching the circuit?
Current flow in a circuit will create a magnetic field. Alternating currents produce fluctuating magnetic field. When a conductor is placed within the magnetic field, fluctuating magnetic fields cause currents to flow in the conductor which further develops a magnetic field. The induction cook-tops use this principle.
When we switch on the device, current flows through the coils located just beneath the cooktop's elements. This creates a fluctuating magnetic field. When any iron rich magnetic cookware (ferromagnetic cookware) is placed in that field, it acts as the second conductor. Now current is induced on it. This current further creates magnetic field which induces smaller electric currents called eddy currents within the cookware. The cookware being made of iron is a poor conductor of electricity which means it offers a high resistance to current. When current runs through a material with a high resistance, much of the current is converted to heat which is utilized for cooking.
In order to generate heat necessary to cook food, a very high frequency of alternating current is necessary. A series of devices like transformer, rectifier and inverter are included in the induction cook-tops. These devices increase the frequency to around 1000 times the input frequency and also protect the appliance and the wiring.