NEIEP Mechanics Practice Exam

In a transformer, if the primary winding has more turns than the secondary winding, what is the expected outcome on voltage?

1. Step-up voltage

2. Step-down voltage

3. Constant voltage

4. Variable voltage

The correct answer is: Step-down voltage

In a transformer, the relationship between the number of turns in the primary and secondary windings directly influences the voltages in each winding. When the primary winding has more turns than the secondary winding, it indicates that the transformer is designed to reduce voltage. This type of transformer is referred to as a step-down transformer. The basic principle at play is Faraday's law of electromagnetic induction, which states that the voltage induced in a coil is proportional to the rate of change of magnetic flux through it and the number of turns in the coil. Therefore, if the primary winding has more turns, it will induce a higher voltage compared to the lower number of turns in the secondary winding. Conversely, a step-up transformer would have more turns in the secondary than in the primary, leading to an increase in voltage. Constant voltage would suggest no change regardless of the turns, which doesn't apply here since the difference in turns will yield a change in voltage output. Lastly, variable voltage suggests fluctuation, which is not a characteristic of transformers under normal operation; transformers produce fixed ratios based on their winding configurations. Thus, the expected outcome in this scenario of having more turns in the primary winding is a step-down voltage in the secondary winding.