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Which of the following devices relies on the principle of eddy currents for its operation?
Induction furnace
Electric kettle
Transformer core insulation
Resistor
Induction furnace
An induction furnace operates on the principle of eddy currents induced within a conducting material by an alternating magnetic field. These eddy currents generate significant Joule heating (I2R loss), which is used to melt metals.
An induction furnace operates on the principle of eddy currents induced within a conducting material by an alternating magnetic field. These eddy currents generate significant Joule heating (I2R loss), which is used to melt metals.
P=Ie2тАЛR
тИЗ├ЧE=тИТтИВtтИВBтАЛ
When a high-frequency alternating current passes through a coil, it creates a rapidly changing magnetic field. This field induces circular eddy currents in the metallic charge placed inside the crucible according to Faraday's Law of Electromagnetic Induction. Due to the electrical resistance of the metal, these currents dissipate energy as heat, causing the metal to melt.
Eddy currents are closed loops of induced current in conductors.
The heating effect is proportional to the square of the induced current.
Higher frequencies increase the penetration depth and heating efficiency.
Skin effect is observed in induction heating, concentrating current at the surface.
High efficiency in melting and heat treatment.
Clean heating process without combustion products.
High initial cost of equipment.
Limited to conductive materials.
Metal melting in steel plants.
Induction hardening and surface treatment of alloys.
Option B (Electric kettle) relies on Joule heating due to ohmic resistance, not electromagnetic induction.
Option C (Transformer core insulation) is designed to minimize eddy currents to reduce losses, not to utilize them.
Option D (Resistor) is a passive component for limiting current, not an inductive heating device.
A is correct тАФ The induction furnace uses induced eddy currents to generate thermal energy for melting metal.
Remember that while eddy currents are desirable in induction furnaces, they are considered parasitic losses in transformers and electric motors, which is why cores are laminated to break the current paths.