In a step-up transformer, what happens to voltage and current?

In a step-up transformer, what happens to voltage and current?

• A. Increases the voltage and decreases the current.
• B. Decreases the voltage and increases the current.
• C. Increases both voltage and current.
• D. Keeps voltage and current the same.

Answer: (A)

In a transformer, the voltages and currents are tied to the turns on the windings and by conserving power (minus losses). A step-up transformer has more turns on the secondary than on the primary, so the secondary voltage rises (Vs > Vp). To keep power roughly the same (Vp × Ip ≈ Vs × Is), the secondary current must drop relative to the primary current (Is < Ip). So the voltage goes up while the current goes down. In real transformers, there are losses, but the inverse relationship between voltage and current with respect to the turns ratio still holds.

In a transformer, the voltages and currents are tied to the turns on the windings and by conserving power (minus losses). A step-up transformer has more turns on the secondary than on the primary, so the secondary voltage rises (Vs > Vp). To keep power roughly the same (Vp × Ip ≈ Vs × Is), the secondary current must drop relative to the primary current (Is < Ip). So the voltage goes up while the current goes down. In real transformers, there are losses, but the inverse relationship between voltage and current with respect to the turns ratio still holds.