In an ideal transformer with a turns ratio of 1:2 (Np:Ns), the secondary voltage is what fraction of the primary voltage under ideal conditions?

In an ideal transformer with a turns ratio of 1:2 (Np:Ns), the secondary voltage is what fraction of the primary voltage under ideal conditions?

• A. Equal
• B. Twice
• C. Half
• D. One-third

Answer: (B)

In an ideal transformer, voltages scale with the turns on each winding. With a turns ratio of 1:2, the secondary has twice as many turns as the primary, so the secondary voltage is Vs = Vp × (Ns/Np) = Vp × 2. That means the secondary voltage is twice the primary voltage under ideal conditions. If you put 120 V on the primary, you’d see about 240 V on the secondary. The other fractions would only occur if the turns ratio were different (equal voltage would require equal turns; half would require Ns/Np = 0.5; one-third would be Ns/Np = 1/3).

In an ideal transformer, voltages scale with the turns on each winding. With a turns ratio of 1:2, the secondary has twice as many turns as the primary, so the secondary voltage is Vs = Vp × (Ns/Np) = Vp × 2. That means the secondary voltage is twice the primary voltage under ideal conditions. If you put 120 V on the primary, you’d see about 240 V on the secondary. The other fractions would only occur if the turns ratio were different (equal voltage would require equal turns; half would require Ns/Np = 0.5; one-third would be Ns/Np = 1/3).