tech99's latest activity
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tech99 replied to the thread Undergrad Special relativity and diffracting beams.I think this phenomenon will occur with any wave, such as sound. The small diameter wavefront seen at optical frequencies may be... -
tech99 replied to the thread High School A question about the rotation of points on a wheel.Another interesting case is the bottom point of a train wheel, which is travelling backwards.
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tech99 replied to the thread Undergrad Chua's oscillator circuit -- Intuitive picture.As a radio engineer, it seems to me to resemble some behaviour which was well known by 1910. If we have two resonant circuits of the...
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tech99 replied to the thread High School Why would sailboat racers prefer a full keel over a fin keel?.Heeling is caused by the couple created by the sideways force of the sails and the opposing sideways lift of the keel. Heeling is...
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tech99 replied to the thread High School Why would sailboat racers prefer a full keel over a fin keel?.May I mention again that the leeway angle is equal to the angle of attack of the keel. It is important that the area of the foil is...
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tech99 replied to the thread Compressive strength of aluminum.For a column in compression, according to Euler's formula, the buckling strength is not sensitive to the yield strength of the material...
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tech99 replied to the thread High School Why would sailboat racers prefer a full keel over a fin keel?.Maybe first consider the function of a fin (or centreboard on a small craft). The sail is a aerofoil in the wind and a fin is an...
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tech99 replied to the thread Undergrad Our Mathematical Universe book -- Since when does light contain voltage?.How are you going to measure potential difference without introducing electrons into the process?
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tech99 replied to the thread Undergrad Our Mathematical Universe book -- Since when does light contain voltage?.If I place an electric circuit, containing a suitable indicator, in the path of an EM wave I can notice a current being created.
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tech99 replied to the thread Removing silver stains.The black stains might be silver halides, in which case sodium thiosulfate will dissolve them. As silver is very toxic, to both people...
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tech99 replied to the thread Electrical breakdown signal across the oil film.I would suggest the 2 volts is related to the work function of the material. I should have thought that oscillation in the GHz region...
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tech99 replied to the thread High School Propagation of Thunder.I also observed similar effects with a sonic boom. When Concorde was flying over the Atlantic, I would often hear the boom when walking...