If the primary voltage is 240 V for this transformer, what is the secondary voltage?

If the primary voltage is 240 V for this transformer, what is the secondary voltage?

• A. 60 V
• B. 240 V
• C. 12 V
• D. 120 V

Answer: (A)

Voltage on the secondary is set by the turns ratio: Vs = Vp × (Ns/Np). With a primary of 240 V and a secondary of 60 V, the ratio Ns/Np is 60/240 = 1/4, meaning the secondary winding has one quarter as many turns as the primary. That’s a step-down by four to one, so 60 V is the correct secondary voltage. If the turns ratio were different, you’d get the corresponding voltage like 1:1 for 240 V, 1:2 for 120 V, or 1:20 for 12 V. In real transformers, power is roughly conserved, so the current on the secondary would be about four times the primary current (ignoring losses).

Voltage on the secondary is set by the turns ratio: Vs = Vp × (Ns/Np). With a primary of 240 V and a secondary of 60 V, the ratio Ns/Np is 60/240 = 1/4, meaning the secondary winding has one quarter as many turns as the primary. That’s a step-down by four to one, so 60 V is the correct secondary voltage. If the turns ratio were different, you’d get the corresponding voltage like 1:1 for 240 V, 1:2 for 120 V, or 1:20 for 12 V. In real transformers, power is roughly conserved, so the current on the secondary would be about four times the primary current (ignoring losses).