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No, on the other hand, you can measure by comparing to a standard of the same time. A lot of common measuring instruments, starting with the ruler, do exactly that. Incidnetally, an AC-excited bridge circuit can meausure capacitance in terms of a standard capacitor, but you can also balance R:C against L:R (taking the obvious meaning). This is more commonly used to measure inductance (in that it's easier to get a stable stnadard capacitor than a stable standard inductor), but there's no reason in principle why you can't measure capacitance in terms of inductance and the ratio of 2 resistors. I would agree... However, M.G.Scroggie's 'Radio Laboratory Handbook' makes the probably valid point that in general it is more accurate to measure something against a standard of the same time (there are fewer 'conversions' to different physical quantities, each of which may not be exact). Said book (of course) treats assorted bridge circuits as methods of measuring 'circuit constants'. As does the _excellent_ 'Measurements in Radio Engineering' by Professor Terman (I am sure everyone here knows who he is. Now, I am sure there are people who know more about electrical measurements than Professor Terman, but I don't think such people are exactly common, and I am darn sure said physics teacher wasn't one of them. -tony