How Laminated Cores Are Better Than Solid Iron Cores?

Laminated cores are used (rather than solid cores) to prevent these eddy currents flowing through circulating currents which have been set by magnetic fields that can break down cores into sheets each coated with insulating material that does not conduct electricity and allows eddy currents to flow.

When it comes to the core material in a transformer if you use solid iron just plain solid iron or any other solid ferromagnetic substance as the core for a transformer you're going to have problems.

Because you're going to get circulating currents in that iron which will heat it up and cause loss and loss of efficiency for your transformer it can in the extreme case heat up the core to the point where it cracks and damages.

Which makes it impossible for these eddy currents to occur, which is what is meant by a laminated transformer core, it's quite effective at 50 or 60 Hertz alternating current for the purpose of power transformers it begins to lose though.

With audio and radio frequencies more often than powdered iron or ferrite for high permeability powdered iron, these types of materials work better in audio and radio frequencies but not so well at alternating current power frequencies like 50 or 60 Hertz then you're best off with a laminated core of thickness in a range of 0.20mm to 0.30mm for each sheet.

Oriented Silicon Steel Core