A thin metal strip fixed at one end is set into transverse vibration by a small periodic force whose frequency can be varied smoothly from very low values to well above the strip’s natural frequency.
(i) Describe how the steady–state amplitude of the strip is expected to change as the driving frequency is increased through the natural frequency, naming the phenomenon that occurs at the maximum amplitude.
(ii) Explain physically why the amplitude decreases again when the driving frequency becomes much higher than the natural frequency.
(iii) Even though the driving force is small, the strip is observed to vibrate with large energy at the maximum amplitude found in part (i). Account for this observation in terms of energy transfer per cycle.