Physics · Electromagnetic Induction · NEET
A solid block is one big conductor. The changing magnetic flux induces large circulating eddy currents in it, and these currents heat the block through I²R loss, wasting energy. A laminated core does the same magnetic job but wastes far less power as heat.
Eddy currents flow in loops in the plane perpendicular to the changing flux. Thin sheets make each loop small, so its area is tiny (less induced emf) and its path is long and narrow (high resistance). Smaller emf plus higher resistance means much smaller current, and heat depends on the square of that current, so losses drop sharply.
If the sheets touched, current could jump across and the core would behave like a solid block again. The insulating layer forces each eddy current to stay trapped inside its own thin lamination, keeping the loops small. The sheets are insulated across their faces but still stacked along the flux direction so the magnetism passes through fine.
No. Lamination only cuts eddy current loss. Hysteresis loss comes from repeatedly reversing the magnetisation of the core and is reduced by choosing a soft magnetic material with a low hysteresis loop, not by slicing. NEET often pairs these two as separate remedies.
Almost not at all. The sheets are stacked so the magnetic flux runs along their length, and iron still fills nearly the whole volume. The thin insulation blocks stray current, not magnetic field lines, so the useful flux and mutual coupling stay high.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Eddy currents are circulating currents induced inside a solid conductor when the magnetic flux through it changes, by Faraday's and Lenz's laws.
A thinner solid core still allows one large loop. Many insulated thin sheets create many tiny high-resistance loops, which is what actually kills the eddy current heat.
They are stacked parallel to the magnetic flux (and to the plane of the flux), so the flux flows along the sheets while eddy loops are cut across them.
In Electromagnetic Induction (eddy currents) and in Alternating Current (transformer energy losses). NCERT lists eddy current loss reduced by a laminated core and hysteresis loss reduced by soft magnetic material.
No. They are wasteful in transformer and motor cores, but useful in electromagnetic braking, induction furnaces and metal detectors.
