A transformer has a primary voltage V1 = 120 V and a turns ratio N2/N1 = 2. What is V2?

• A. 60 V
• B. 240 V
• C. 120 V
• D. 480 V

Answer: (B)

In an ideal transformer, the secondary voltage scales with the turns ratio: V2 = (N2/N1) × V1. Here the turns ratio is 2, so the output voltage is twice the input. V2 = 2 × 120 V = 240 V. This is a step-up transformation, meaning the voltage increases while the current decreases correspondingly (I2 = (N1/N2) × I1) if power is conserved. The other voltages would correspond to different turns ratios: 60 V would require a ratio of 0.5 (step-down), 120 V would require a ratio of 1 (no change), and 480 V would require a ratio of 4 (larger increase than given).