Which of the following is the best description of resonance?

Resonance is best described as a natural frequency of an object that is being excited by external vibrations. When a system is subjected to vibrations at its natural frequency, it can experience a significant increase in amplitude, which is characteristic of resonance. This phenomenon occurs because the system efficiently absorbs energy at this frequency, leading to large oscillations that enhance the motion of the system.

In practical scenarios, understanding resonance is crucial, especially in applications related to mechanical and structural engineering, where systems must be designed to avoid resonance to prevent excessive vibrations that can lead to failure or damage. Recognizing the natural frequencies of components helps engineers to either avoid exciting these frequencies or to appropriately damp the vibrations.

The other options describe aspects of vibrational characteristics but do not capture the essence of resonance. The maximum vibration potential refers to the limits of vibration amplitude irrespective of frequency. The amplitude of steady-state vibrations pertains to how much vibration occurs when a system reaches a periodic steady-state, but does not necessarily imply resonance. A phase difference between input and output motion describes the relationship between two vibrations, which is an important aspect but does not define resonance itself. Hence, the correct response highlights the unique and critical feature of resonance as a natural frequency excited by vibration.