Interpreting displacement-time graph for wave properties

Steps:

• The graph plots displacement against time for one point on the string, showing simple harmonic motion.
• Points X and Y have the same displacement value, corresponding to the maximum displacement (amplitude).
• The horizontal separation XY measures the time for one full oscillation cycle.
• This time interval defines the time period of the wave.

Why B is correct:

• In a displacement-time graph, points with equal amplitudes (max displacements) separated by the time period complete one wave cycle, per the definition of periodic waves.

Why the others are wrong:

• A: Period is a time interval, not a property that points X and Y share equally; amplitude is a displacement magnitude, not a time separation.
• C: Wavelength is a spatial distance between wave crests, irrelevant to a time-based graph.
• D: Wavelength is spatial, not temporal; displacement describes y-values, not the XY time separation.

Final answer: B