Which one out of the following is not an application of eddy currents?

The correct answer is Option (1) → Transformers

Eddy currents are currents induced in a bulk piece of metal by a changing flux. They can be put to use, or they can be a nuisance that has to be reduced.

Option (1) Transformers — Correct answer. In the core of a transformer eddy currents only waste energy as heat, so the core is built of thin insulated laminations to keep them small. They are not used here.

Option (2) Speedometers — an application. The eddy currents induced in a metal drum by a rotating magnet give a drag that depends on the speed.

Option (3) Magnetic Brakes — an application. The eddy currents induced in a moving metal part oppose its motion, as in some electric trains.

Option (4) Induction furnace — an application. Large eddy currents heat the metal until it melts.

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Eddy Currents – “… This fact is helpful in reducing eddy currents in the metallic cores of transformers, electric motors and other such devices in which a coil is to be wound over metallic core. Eddy currents are undesirable since they heat up the core and dissipate electrical energy in the form of heat.”

Eddy Currents – “… Eddy currents are used to advantage in certain applications like: (i) Magnetic braking in trains: … (iii) Induction furnace: Induction furnace can be used to produce high temperatures and can be utilised to prepare alloys, by melting the constituent metals.”