What does the efficiency of a transformer indicate?

The efficiency of a transformer indicates the percentage of power that is not wasted due to heat dissipation and is effectively transferred from the primary winding to the secondary winding. This concept is crucial for understanding how well the transformer converts electrical energy from one circuit to another without significant losses.

When a transformer operates, some energy is inevitably lost as heat due to resistance in the windings and other factors, but a highly efficient transformer minimizes these losses, meaning that a larger proportion of the input power is delivered as output. Therefore, the efficiency reflects the good design and materials used, aiming for optimal energy transfer with minimal waste.

In contrast, other options focus on aspects that do not accurately capture the definition of efficiency. For example, the idea of wasted power remains relevant to understanding losses, but it fails to encapsulate the positive aspect of efficiency that indicates effective energy transfer. The total power rating of windings or the maximum power output does not directly relate to how efficiently the transformer functions during its operation.