When a transformer is designed, what most determines the output voltage from the secondary?

The output voltage from the secondary of a transformer is primarily determined by the ratio of primary to secondary turns of wire in the transformer coils. This fundamental relationship is expressed in the transformer equation, which states that the voltage across the primary winding (input) is to the voltage across the secondary winding (output) as the number of turns on the primary is to the number of turns on the secondary.

When designing a transformer, engineers calculate the necessary turns ratio to achieve the desired output voltage. For instance, if a transformer has more turns on the secondary than on the primary, the output voltage will be higher than the input voltage. Conversely, if there are fewer turns on the secondary, the output voltage will be lower. This design principle is critical for ensuring that the transformer meets its intended application and load requirements.

The other factors, although they play a role in the overall performance and efficiency of the transformer, do not directly determine the output voltage. The power rating relates to how much power the transformer can handle without overheating, the core material affects the efficiency and operation but not directly the voltage output, and the frequency can influence reactance and potential losses but is not the principal determinant of output voltage. Thus, the turns ratio is the key factor in establishing the transformer