What does a lower transformer efficiency indicate?

A lower transformer efficiency indicates a higher input power compared to output power because it suggests that a greater portion of the input energy is being lost rather than converted into usable output energy. Efficiency is calculated as the ratio of output power to input power, so if the efficiency is low, this means the output power is significantly less than the input power, indicating losses often attributed to heat, magnetic losses, and other factors in the transformer.

In contrast, other options do not align with this understanding. For instance, lower efficiency does not imply more effective energy conversion or optimal performance; rather, it signifies inefficiencies in the transformation of energy from input to output. Similarly, minimal energy loss cannot be associated with low efficiency, as that would contradict the very premise of a lower efficiency implying significant energy losses. Therefore, the understanding that lower efficiency correlates with higher input power than output power is accurate and reflects the nature of transformer performance.