the core of a transformer is usually laminated in order to

Step 1: Analyze the question The question asks why a transformer's core is made of thin insulated sheets (laminations) instead of one solid block of iron.

Step 2: The concept A transformer works by changing magnetic flux in the core. This changing flux induces an emf in the secondary coil. It also induces unwanted circulating currents inside the iron core itself. These are called eddy currents.

• Eddy currents flow in closed loops inside the core.
• They produce heat (I²R loss), which wastes energy and can overheat the transformer.

Step 3: How lamination helps The core is made of thin sheets of iron, each insulated from the next by varnish or oxide. This:

• Breaks up the paths available to the eddy currents.
• Increases the resistance to these currents.
• Greatly reduces the eddy current and the heat loss.

Step 4: Check the options

• A. Reduce magnetic leakage: Wrong. Leakage is reduced by winding the coils closely or on the same core, not by lamination.
• B. Reduce eddy current: Correct. This is the purpose of lamination.
• C. Prevent vibration: Wrong. Vibration (humming) is reduced by clamping or tightening the core.
• D. Make magnetic reversal easier: Wrong. This relates to hysteresis loss, which is reduced by using soft iron, not by lamination.

Tip: Remember "Laminate = Limit eddy". Lamination reduces eddy currents. Soft iron reduces hysteresis loss. Thick copper wire reduces resistive (copper) loss. WASSCE often asks you to match each energy loss in a transformer to its remedy.