Transformers are designed so that energy losses are reduced to a minimum. This is achieved through which of…

Analyze the question: It asks which design features reduce energy losses in a transformer. We need to check each statement (I, II, III).

Concept: Energy losses in transformers

• Eddy current losses: Changing magnetic flux induces circulating currents in the core, which produce heat. These are reduced by laminating the core, that is, building it from thin sheets insulated from each other.
• Hysteresis losses: Energy is wasted when the core is repeatedly magnetized and demagnetized. These are reduced by using a soft iron core, which magnetizes and demagnetizes easily.
• Flux leakage losses: These are reduced by designing an efficient core shape (for example, a closed loop or shell type) so that all the flux links the primary and secondary coils.
• Copper (resistive) losses: These are reduced by using thick copper wire of low resistance.

Check each statement:

• I. Using soft iron: TRUE. It reduces hysteresis loss. (The question says "iron ore", but this is clearly a slip for "iron core", so we treat it as the soft iron core.)
• II. Laminating the core: TRUE. It reduces eddy current loss.
• III. Designing an efficient iron core: TRUE. A well-designed core reduces flux leakage and so improves efficiency.

All three statements are correct, so the answer is I, II & III only.

Note on the wording: The word "ore" in statement I is probably a typo in the question. Strictly speaking, soft iron ore is not used in transformers, but the intended meaning is soft iron core.

Exam tip: Remember the transformer losses and their remedies:

• Eddy currents → laminated core
• Hysteresis → soft iron
• Flux leakage → good core design
• Copper loss → thick copper wires

When a JAMB question lists several of these as "ways to reduce losses", the answer is often "all of the above".