Answer: A step-down transformer changes the magnitude of the voltage in an alternating current (AC) electrical signal. It reduces the voltage of the AC signal by using a winding ratio between the primary (input) and secondary (output) coils that is less than 1:1.
Explanation: For example, if the winding ratio of a step-down transformer is 1:0.5, the output voltage of the secondary coil will be half the magnitude of the input voltage of the primary coil. In this case, the transformer would change the AC voltage from a higher value to a lower value.
The transformer does not change the frequency of the AC signal, which is determined by the source of the electrical power. The transformer also does not change the waveform of the AC signal, which is typically a sinusoidal wave.