Which statement describes a step-up transformer?

A step-up transformer is designed to increase voltage from the input (primary) side to the output (secondary) side. This is accomplished by having more turns of wire on the secondary winding compared to the primary winding. When alternating current flows through the primary winding, it creates a magnetic field that induces a voltage in the secondary winding. The ratio of turns between the primary and secondary windings determines whether the voltage will increase or decrease.

In the context of a step-up transformer, the primary winding has fewer turns than the secondary winding. This relationship is crucial for stepping up the voltage. For instance, if the secondary winding has twice as many turns as the primary, the voltage in the secondary will be approximately twice that of the primary.

The correct answer highlights that in a step-up transformer, the design involves the relationship between turns in the windings, which is key to its functioning. The other options do not accurately describe the fundamental operation of a step-up transformer. For instance, fewer turns in the secondary winding contradicts the step-up principle, and higher voltage in the primary winding typically does not relate to the transforming action of a step-up mechanism. Additionally, a transformer does not generate electrical energy; it simply converts voltage levels based on the turns ratio.