In a step-down transformer, the turns ratio is such that the secondary coil has how many turns compared to the primary?

In a step-down transformer, the function is to reduce the voltage from the primary coil to the secondary coil. This reduction is achieved by having fewer turns in the secondary coil compared to the primary coil. The turns ratio is essential in determining how voltage is transformed; when there are fewer turns in the secondary coil, this results in a lower output voltage.

The relationship established by the turns ratio is that the voltage across the primary is proportional to the number of turns in the primary compared to the secondary. Therefore, in a step-down transformer, the secondary must indeed have fewer turns than the primary to accomplish a decrease in voltage while allowing for an increase in current, in line with the principles of the conservation of energy.

In this context, having more turns in the secondary (as one of the other options suggests) would indicate a step-up transformer instead, where the voltage increases rather than decreases. A transformer with the same number of turns in both coils would not change the voltage. Double the turns in the secondary would further increase the voltage, contradicting the function of a step-down transformer.