Step-down transformer facts: Which statement correctly describes a step-down power transformer (ideal case, ignoring losses)?

Introduction / Context:A step-down transformer reduces voltage from primary to secondary while ideally conserving power (P ≈ constant, ignoring losses). Consequently, when voltage goes down, current must increase proportionally to maintain the same power. Recognizing this trade-off is central to transformer-based power conversion.

Given Data / Assumptions:

• Ideal transformer relationships apply.
• Step-down implies V_s < V_p (secondary voltage less than primary).
• Power conservation approximation: V_p * I_p ≈ V_s * I_s.

Concept / Approach:For an ideal transformer: V_s/V_p = N_s/N_p and I_s/I_p = N_p/N_s. If V_s is decreased (N_s < N_p), then I_s increases relative to I_p, assuming the same load power transfer. Thus, step-down in voltage implies step-up in current.

Step-by-Step Solution:Recognize step-down: V_s < V_p.Apply ideal relation: I_s/I_p = V_p/V_s > 1.Therefore I_s > I_p.Conclude the correct statement: secondary current exceeds primary current.

Verification / Alternative check:Example: If V_p = 120 V, V_s = 12 V (10:1). Delivering 120 W implies I_p = 1 A and I_s = 10 A, confirming the current increase on the secondary.

Why Other Options Are Wrong:(a) contradicts step-down definition. (c) and (d) are unrelated statements about different circuits and are not transformer properties.

Common Pitfalls:Confusing voltage and current ratios; forgetting that power is approximately conserved (minus losses), so as voltage drops, current rises.

Final Answer:Secondary current is greater than primary current (for the same power level)