Glass Stories

Glass and Resonance We have all heard stories of how opera singers can shatter glass upon hitting a particular note. However, how plausible is this notion? In order to shatter glass, a singer's voice has to be able to match the frequency of the glass. (Every object has a resonant frequency, which is the natural frequency at which an object vibrates.) If you blow on the edge of a glass, you will hear a resonant hum, and if you keep blowing, you can even create a tune - this sound is the unique resonant frequency of the glass. The singer would have to sing very loudly: precisely producing a note of about 135 decibles, which is more sonic boom than pertaining to anything musical. The human threshold for pain is about 120 decibels. The note would have to be maintained for the duration of at least two to three seconds for the right vibration to build up, so the glass could shatter. In the late 70s, laboratory experiments with a professional soprano and a trumpet player showed that neither could shatter glass. The only singer who has apparently succeeded is the famed tenor, Enrico Caruso, but the validity of this claim is a matter of conjecture. Glass and Wine Why do wine glasses have such long stems? Wine enthusiasts proclaim that it is essential in order to prevent the heat of one's hand on the glass from warming the wine. Any drink that is chilled should be in a glass with a stem. Equally important is the aesthetics of a fine stem, which enhances the pleasure of the experience. By contrast, fine scotch or cognac is drunk from a snifter glass, which has a short stem. The stem in the snifter should be wedged between one's middle and ring finger, with the palm and fingers wrapped around the bowl of the glass, to gently warm the whisky/brandy and allow the aromas to come to the fore. Glass and Computers Anyone who uses a computer knows that an optical mouse does not work on a glass table! Because optical mice use an LED and a camera to rapidly, capture images of the surface beneath the mouse. This information is analyzed by a DSP (Digital Signal Processor), which is used to detect imperfections in the underlying surface, and determine motion. Some materials, such as glass, mirrors or other very shiny, uniform surfaces interfere with the ability of the DSP to analyze the surface beneath the mouse. Since glass is transparent and uniform, the mouse is unable to pick up enough imperfections in the underlying surface to determine motion. Mirrored surfaces are also a problem, since they constantly reflect back the same image, causing the DSP not to recognize motion properly. When the system is unable to see surface changes associated with movement, the mouse will not work properly. Glass and Household Cleaning glass is the big 'bug bear' of most homeowners! The endless build up of soap scum lurking on your tiles and soap racks, and the soapy film on shower doors is like the invasion of Alien 5! Here are a few handy hints on how to keep the alien out of your home. Some say that the best way to get the film off glass doors is to use a no-wax floor cleaner. All you do is wipe it on and make sure you clean it off very well. Vinegar is a close second - you can also add vinegar to your dishwasher or sink, which will get rid of any soap residue and give your dishes an extra sparkle. Ammonia can also clean glass. You can also make your own ammonia solution by combining ammonia and water. Use a spray bottle and spray directly onto the surface. Use a sponge or stiff-bristled brush to scrub affected areas. Wipe clean, and rinse well. Newspaper has enough friction to clean the gunk off and is smooth enough to act as a cleaning cloth.