What effect does an increased number of turns in the secondary coil of a transformer have on the circuit’s voltage?

An increased number of turns in the secondary coil of a transformer results in an increase in voltage. This principle is grounded in the transformer's operation, governed by the relationship between the number of turns in the primary and secondary coils and the voltages across them.

According to the transformer equation, the voltage ratio between the primary and secondary coils is proportional to the turns ratio. When there are more turns in the secondary coil compared to the primary coil, the transformer steps up the voltage. This means that if the secondary coil has more turns, it effectively captures more of the magnetic flux generated by the primary coil, thus inducing a higher voltage.

For example, if the primary coil has 10 turns and the secondary coil has 20 turns, the voltage in the secondary coil will be twice that of the primary coil, assuming ideal conditions with no losses. This principle is essential in applications where voltage needs to be increased for efficient power transmission or specific device requirements.

In contrast, the other options do not hold true in the context of transformer operation. An increase in turns does not decrease voltage, has a direct effect on the voltage, and does not inherently lower current without considering the load on the circuit, which is independent of the turns ratio.