Shelli is a student describing the resonance of a metal beam. she demonstrates that the sound dims when the beam is vibrated at a certain frequency.
what does she most likely say in response to the dimming sound?
a “this is not the natural frequency of the beam.”
b “this is the natural frequency of the beam.”
c “the decibels are increasing.”
d “the amplitude is not increasing.”

The correct answer is “This is not the natural frequency of the beam.”

Explanation:

Resonance is a phenomenon which occurs when the applied frequency on the object is equal to its natural frequency.

When resonance occurs the amplitude of the vibrating object becomes large.

Loudness depends on the amplitude. If the amplitude is low then the sound becomes softer. If the amplitude is large  then the loudness will become more.

In the given problem, Shelli is a student describing the resonance of a metal beam. She demonstrates that the sound dims when the beam is vibrated at a certain frequency. She wants to say in response to the dimming sound that this is not the natural frequency of the beam.

As the dimming sound shows that the amplitude of the sound is low. But it cannot happen in the case of resonance.

Therefore, the correct option is A.

wavelength variability is the right one