Single correct · +4 / −1
Eddy current losses in a transformer core are reduced by:
- (a) using a thicker iron core
- (b) using a laminated core
- (c) increasing current
- (d) decreasing turns
Answer and solution
Answer (b) using a laminated core
Solution
Physics sir · 4 steps
Eddy currents need wide loops of iron to flow in, so slice the core thin and break those loops.
- Origin of eddy currents. The alternating flux in the core induces an emf inside the iron itself. Iron conducts, so this emf drives closed loops of current inside the core, called eddy currents, which waste energy as heat.
- Why lamination helps. A laminated core is made of thin iron sheets, each coated with an insulating layer such as varnish. The sheets lie parallel to the flux, so each eddy current loop is confined to one thin sheet, and that raises the resistance of its path.
P_(eddy) ∝ t²
- Thinner means less loss. Eddy current loss grows with the square of the sheet thickness t. Halving the thickness cuts the loss to about one quarter.
- So. Eddy current losses are reduced by using a laminated core, which is option (b).
The idea to keep. To fight eddy currents, increase the resistance of their path: thin insulated laminations do this. Loss goes as thickness squared, so thinner sheets help a lot.
Answer from the NTA final answer key. Solution by PrepWiser.