FCC Exam Question: 3-21C6
A power transformer has a primary winding of 200 turns of #24 wire and a secondary winding consisting of 500 turns of the same size wire. When 20 volts are applied to the primary winding, the expected secondary voltage will be:
Explanation: Transformers convert AC voltage levels based on the ratio of turns in their windings. The relationship between the primary voltage ($V_P$), secondary voltage ($V_S$), primary turns ($N_P$), and secondary turns ($N_S$) is directly proportional: $V_S / V_P = N_S / N_P$. In this problem: $V_P = 20$ volts $N_P = 200$ turns $N_S = 500$ turns We can calculate the secondary voltage ($V_S$): $V_S = V_P \times (N_S / N_P)$ $V_S = 20V \times (500 / 200)$ $V_S = 20V \times 2.5$ $V_S = 50V$ Thus, the expected secondary voltage is 50 volts. The other options are incorrect because they do not reflect this fundamental turns ratio. The wire size affects the current capacity of the transformer, not the voltage transformation ratio.
3-51G3
3-67J3
3-81L5
3-17B1
3-73K3
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Includes Elements 1, 3, 6, 7R, 8, and 9.