Relationship between harmonics and wave amplitude

[PH7SICS]

What is the relationship between harmonics and wave amplitude in a resonant object?

Lets say we have an object which has a natural resonant frequency of 50hz. we connect that object to a signal generator set at 50hz and note the amplitude of the oscillations the object. Next we go up one harmonic to 100hz and again note the amplitude. If we were to continue going up the harmonic scale and plotted frequency against amplitude what would be the relationship? I know as you go up the scale the amplitude will go down but not sure by how much.

 

[Feldoh]

Thinking about it I think that it depends upon your system and the response of your system to the input. Do you have a specific example in mind?