Why is the primary winding wire of a voltage step-up transformer usually a larger size than that of the secondary winding?
To improve the coupling between the primary and secondary
To accommodate the higher current of the primary✓Correct answer
To prevent parasitic oscillations due to resistive losses in the primary
To ensure that the volume of the primary winding is equal to the volume of the secondary winding
Explanation
Apart from losses the power going in equals the power coming out, so the low-voltage primary of a step-up transformer must carry proportionally more current than the high-voltage secondary, and heavier wire is needed to handle it. Wire size does not set the coupling between windings.