Which of the following indicates a good regulation in a transformer?

A small difference between no load and full load in a transformer indicates good regulation. This means that the output voltage of the transformer remains relatively stable when the load changes from no load to full load conditions. Good voltage regulation is crucial in electrical systems because it ensures that the electrical equipment receives a consistent voltage, which is important for optimal performance and to prevent damage.

Transformers with good regulation are designed to minimize the variations in output voltage due to changes in load. If the difference between no load and full load is small, it demonstrates that the transformer is effectively managing load variations, maintaining steady voltage, and efficiently delivering power. Thus, option B emphasizes the effectiveness of the transformer in maintaining output voltage stability, which is a key characteristic of good transformer performance.