In basic wave and communication theory, the distance a signal’s energy travels during one complete cycle is called the signal’s _________. Select the correct term.

Introduction:
To analyze electromagnetic and acoustic waves, it is essential to distinguish time-domain and spatial-domain properties. The question targets the spatial measure associated with a single cycle of oscillation, a cornerstone concept in RF, optics, and acoustics.

Given Data / Assumptions:

• Uniform medium with constant propagation speed v.
• Periodic waveform with frequency f and period T = 1 / f.
• Standard terminology used in physics and communications.

Concept / Approach:
Wavelength (lambda) is defined as the physical distance a wave travels in one period. It relates to speed and frequency via lambda = v / f. Do not confuse wavelength with period (time per cycle), frequency (cycles per second), or amplitude (maximum displacement or field strength).

Step-by-Step Solution:
1) Recognize the question asks for a distance per cycle (spatial measure).2) Identify correct term: wavelength is distance traveled in one cycle.3) Use relationship if needed: lambda = v / f ensures units of meters.4) Conclude that the appropriate term is “wavelength”.

Verification / Alternative check:
Example: In free space, v ≈ 3 * 10^8 m/s. For f = 100 MHz, lambda = 3 m, which matches widely taught VHF antenna dimensions.

Why Other Options Are Wrong:
Amplitude: magnitude of oscillation, not a distance per cycle.
Frequency: cycles per second; temporal rate, not a spatial length.
Period: time for one cycle, not a distance.
Phase lead: a relative angle shift, not a spatial measure.

Common Pitfalls:
Interchanging period and wavelength because both describe “one cycle.” Always check units (seconds vs meters).

Final Answer:
wavelength