Question 6A311

A transformer's primary impedance is predominantly inductive reactance ($X_L$), which is directly proportional to frequency ($X_L = 2\pi f L$). When the source frequency ($f$) increases from 60 Hz to 120 Hz, the inductive reactance and therefore the transformer's total impedance will increase. This confirms (A). According to Ohm's Law ($I = V/Z$), if the source voltage ($V$) remains the same but the impedance ($Z$) increases, the current ($I$) drawn by the transformer from the source must decrease. This confirms (B). With a reduced primary current, less power is drawn from the source ($P = V \times I \times \cos(\theta)$). As less power is drawn from the primary, less power can be transferred to the secondary and delivered to the load, assuming the transformer is still operating efficiently. This confirms (C). Since all three statements (A, B, and C) are correct based on fundamental AC circuit theory, option (D) is the correct answer.