### Re: What material resonate at any frequency it recieves from it's surroundings?

Date: Fri Jun 29 14:43:58 2001
Posted By: John Balbach, Physicist
Area of science: Physics
ID: 993614577.Ph
Message:

Your question is somewhat vague, and therefore difficult to answer. The simplest answer is "nothing". There is nothing that will resonate at any frequency without some sort of adjustment. Let me explain.

Resonance occurs when an external event excites a normal mode of the resonating object. An object has a normal mode at a particular frequency when a standing wave (a wave that reinforces itself, and so does not suffer from self-cancellation) can be excited. This depends on certain physical properties of the material, and on the size of the object.

Some examples:

• tuning forks have normal modes at their rated frequency. This frequency is determined by the material (steel, aluminum and copper tuning forks of the same size would have different frequencies) and by the size (a set of tuning forks come in all sorts of different sizes.
• Radios are tuned to certain frequencies by varying the capacitance or the inductance of a tuned circuit.
• Unpaired electrons and certain atomic nuclei will resonate at various frequencies depending on the size of magnetic field that they sense. This is called magnetic resonance. The resonant frequency is largely determined by the gyromagnetic ratio of the nucleus (or electron) but also by the environment around the nucleus (or electron).

I would have to know a lot more about what kind of resonance you are looking to excite before I can suggest a material, shape or device. For some reading on your own, you might try any introductory physics text, a text about the physics of sound and music, or a book about Radiofrequency circuit design.

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