Transmission-line theory — infinite (endless) line behavior Statement: In an infinite line, the input impedance at every point equals the characteristic impedance Z0. Choose the correct truth value.

Introduction / Context:The concept of an ‘‘infinite’’ transmission line is a theoretical construct where the line extends without termination, so no reflection ever returns. Understanding its input impedance clarifies why a finite line perfectly terminated in Z0 appears the same to the source.

Given Data / Assumptions:

• Uniform, lossless or low-loss line with characteristic impedance Z0.
• No discontinuities or terminations to cause reflections.

Concept / Approach:With no reflection, the voltage and current form a pure traveling wave. The ratio V/I remains constant everywhere and equals Z0. Thus, the input impedance looking into any point of an infinite line is Z0, independent of distance along the line.

Step-by-Step Reasoning:

Verification / Alternative check:Equivalently, a finite line terminated in Z0 has Γ = 0 and presents Z0 at its input, mimicking the infinite-line condition.

Why Other Options Are Wrong:

• False: would imply some position-dependent impedance despite the absence of reflections, which contradicts traveling-wave theory.

Common Pitfalls:Confusing standing-wave patterns (which require reflections) with the reflection-free traveling-wave case.

Final Answer:True