What device reduces the input voltage to a lower voltage in an electrical circuit?

What device reduces the input voltage to a lower voltage in an electrical circuit?

• A. Step-down transformer
• B. Auto transformer
• C. Transformer
• D. Regulator

Answer: (A)

Reducing voltage in an AC circuit is achieved by a transformer, specifically a step-down transformer. In a transformer, voltage changes according to the turns ratio: Vp/Vs = Np/Ns. When the secondary winding has fewer turns than the primary, the secondary voltage is lower than the primary voltage, giving a lower output while still transferring power efficiently. This setup also provides galvanic isolation between the input and output circuits in many designs. An autotransformer can also reduce voltage, but it shares a common winding and doesn’t provide isolation. A regulator actively controls voltage and is not based on inductive coupling between separate windings, so it isn’t the typical device for simply stepping down voltage. A general transformer can either step up or step down depending on the turns ratio, but describing it as step-down precisely communicates lowering the voltage with isolation.

Reducing voltage in an AC circuit is achieved by a transformer, specifically a step-down transformer. In a transformer, voltage changes according to the turns ratio: Vp/Vs = Np/Ns. When the secondary winding has fewer turns than the primary, the secondary voltage is lower than the primary voltage, giving a lower output while still transferring power efficiently. This setup also provides galvanic isolation between the input and output circuits in many designs. An autotransformer can also reduce voltage, but it shares a common winding and doesn’t provide isolation. A regulator actively controls voltage and is not based on inductive coupling between separate windings, so it isn’t the typical device for simply stepping down voltage. A general transformer can either step up or step down depending on the turns ratio, but describing it as step-down precisely communicates lowering the voltage with isolation.