Transformer basics — If a transformer has a turns ratio of 5:1 defined as Ns:Np = 5:1, what does this imply about the relative number of turns?

Introduction:
Turns ratio definitions must be explicit. The common convention is to state the ratio as Ns:Np (secondary to primary) or V2:V1 for ideal transformers. Clarity prevents design and measurement mistakes in step-up vs. step-down applications.

Given Data / Assumptions:

• Turns ratio is stated as 5:1 and explicitly defined Ns:Np = 5:1.
• Ideal transformer behavior for conceptual understanding.
• Same frequency on both windings; negligible losses.

Concept / Approach:

In an ideal transformer, V2/V1 = Ns/Np and I2/I1 = Np/Ns. Therefore, Ns:Np = 5:1 means five times as many turns on the secondary as on the primary. This configuration is a step-up transformer for voltage (and step-down for current).

Step-by-Step Solution:

Verification / Alternative check:

Practical measurements with open-circuit secondary show V2 approximately five times V1 for this ratio, confirming the turns relationship.

Why Other Options Are Wrong:

• more primary turns: Opposite of the defined ratio.
• more secondary current: Inverse is true; current is reduced when turns and voltage are stepped up.
• source/load impedance statements: Not directly implied by turns ratio alone without context.
• equal turns: Contradicts the 5:1 statement.

Common Pitfalls:

• Confusing Ns:Np with Np:Ns; always specify orientation.
• Ignoring that stepping up voltage steps down current for similar power.

Final Answer:

more secondary turns than primary turns