Resonance

=**What is resonance?**=

Resonance is defined as the phenomenon that objects begin to vibrate when they receive vibrations near to its natural frequency. When objects receive bursts of energy (wavelike vibrations) at the same frequency as it would typically put off energy, the object will absorb the energy and begin to vibrate itself, as opposed to being the a "brick wall" where the wave stops. The phenomenon is perhaps most famous as an opera stunt. When a wine glass is tapped, it will sound a certain note. This note is its natural frequency. If a singer is able to and does sing a note at that frequency, the glass will receive those waves and begin to vibrate. Then, should the sound reach a certain decibel level, the vibrations in the glass will become to great for the material to withstand. And the glass shatters.

A questionable example of [|resonance]. A real example of [|resonance], even if it doesn't have sound, and [|another] with sound.

We can be fairly certain that the first video above is fake for a couple reasons. Perhaps the most obvious reason is that human flesh does not have any "natural frequency" anywhere within humans' hearing range, the final resonant breakage certainly cannot be caused only by the sung note. The second reason is that the first three examples of "shattering by resonance" should not have occured at the same frequency note. the pitches that those glass pieces would have emmited naturally are most likely not all the same, which was true in the video; the same frequency vibration (note) breaks all three. Finally, the manner in which they break is not realistic. See the second link to compare.

The other two videos above show a speaker vibrating at the wine glass' natural frequency, causing the glass to very visibly vibrate until it shatters from the stress. Note also that, from the top view, the wave can be seen traveling around the rim of the glass, simply demonstrating that it is a wavelike vibration: not just a random shaking... media type="custom" key="2040652"media type="custom" key="2039606" The second of these videos demonstrates exactly the same concept as with a vibrating wine glass; the vibrations given off by the first tuning fork are detected by the second fork, and because they have the same frequency, the second fork begins to vibrate. Although we cannot specifically see it vibrate, the small piece of paper resting on top is visibly vibrated off. Now, had those forks been of different frequencies, the demonstration would not have worked.

The first of these two videos shows how resonance applies to vibrations other than the sound of an singer or tuning fork. Resonance will occur with any form of vibration, of which sound is merely a specific type. This has become fairly well known through the potential tragedy which occurred at [|Tacoma Narrows Bridge] (Note: the incident was not fatal, even the dog was saved). If the culprit is in fact resonance, the bridge vibrations were caused by wind forming spirals on the downwind edge of the bridge, and these spirals alternating between coming from above and below the span. This effect is know as [|vortex shedding]. However, it has been strongly [|argued] that this is not what happened, so it cannot be held as fact.