A transformer has a primary impedance of 60 Ω and a secondary impedance of 120 Ω. What is the impedance ratio (primary : secondary)?

Introduction / Context:
Impedance ratio is a straightforward comparison often used when referencing impedances between transformer windings. It relates to the square of the turns ratio but can also be computed directly if both effective impedances are given.

Given Data / Assumptions:

• Z_primary = 60 Ω.
• Z_secondary = 120 Ω.
• We seek Z_primary : Z_secondary as a numeric ratio.

Concept / Approach:
The impedance ratio (primary : secondary) is simply Zp/Zs when both values are expressed in the same units. If needed, turns ratio a satisfies Zp/Zs = (Np/Ns)^2, but here a direct division suffices.

Step-by-Step Solution:
Compute ratio: Zp/Zs = 60 / 120.Simplify: 60 / 120 = 0.5.Therefore the impedance ratio is 0.5 (primary lower than secondary).

Verification / Alternative check:
Turns ratio check: If Zp/Zs = 0.5, then Np/Ns = sqrt(0.5) ≈ 0.707, consistent with secondary having higher impedance.

Why Other Options Are Wrong:
0.25 and 4: correspond to a 1:2 impedance ratio in the opposite sense.180: unrelated magnitude.None: incorrect because 0.5 is correct.

Common Pitfalls:
Inverting the ratio (secondary : primary instead of primary : secondary) or mixing turns and impedance ratios.

Final Answer:
0.5