Monday, 2020-08-03, 2:39 PM
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RD's Science Pages

Video demonstrations

This is an interesting video showing the increasing reactivity of alkali metals with air and water as you go from lithium to cesium. The quantity of metal used is small, suitable for a lab demo. But it is very dangerous to actually do it in a class room or lab, and samples of rubidium or cesium metal are difficult to obtain. But this video demo is something teachers and students can enjoy safely, and is very informative. Switch on the speakers, please!

More information and demonstrations about alkali metals are available in these videos.
Switch on the speakers, please!

Lithium               Sodium               Potassium               Rubidium

                      Cesium(1)            Cesium(2)            Cesium(3)                Francium

Not only stretched strings, drums and tuning forks, all objects including electrons, buses and buildings have a natural vibration frequency. Absorption of this frequency forces the object to respond by highly amplified vibration. This phenomenon is called "resonance". An extreme example of this phenomenon is provided by the Tacoma bridge collapsing in the wind, depicted in this video. There is probably no better illustration for this phenomenon. Switch on the speakers, please!

Get more details about the Tacoma bridge from Wikipedia.

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