Circuit and electromagnetism basics
An AC voltage of 100 V (RMS) is applied to the primary of an ideal transformer with 1000 primary turns and 100 secondary turns. What is the secondary voltage (RMS)?
- A1000 V
- B100 V
- C10 V
Show answer and explanation
Answer: C. 10 V
In an ideal transformer, voltage is proportional to the number of turns: V2 = V1 × N2/N1 = 100 V × 100/1000 = 10 V. Because power is conserved, current is inversely proportional to turns, so the secondary current is ten times the primary current. A transformer transfers voltage through a changing magnetic flux, so it cannot convert DC voltages.
- A. 1000 V uses the turns ratio upside down.
- B. 100 V is just the primary voltage, with no transformation.
- C. Correct. 100 V × 100/1000 = 10 V.
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