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I haven't done lab work in ages, but I seem to recall both names being used to describe things we used to measure voltage. (Don't hold me to that, though!) Wikipedia has a link describing the use of a potentiometer as a voltmeter. From reading the page briefly, it sounds like the potentiometer taps off (a variable amount) of current from a circuit to measure voltage, while a voltmeter isn't variable, and is usually designed to tap off as little current as possible. Am I right in thinking this?
The sentences that led me off track in Wikipedia were "A potentiometer is an instrument for measuring the potential (or voltage) in a circuit. The instrument taps off a fraction of a known voltage from a resistive slide wire and compares it with the unknown voltage by means of a galvanometer."
That reminds me of another important difference.The other essential "component" in the circuit, is a human being! Someone has to adjust the potentiometer to find the null point of the galvanometer.
Quote from: Geezer on 28/07/2010 06:31:55That reminds me of another important difference.The other essential "component" in the circuit, is a human being! Someone has to adjust the potentiometer to find the null point of the galvanometer. Automatic, self-balancing potentiometers have been used. Good old fashioned chart recorders were based on them.It's true that apotentiometer can only give you the ratio of to voltages, if oner of them is a standard cell then that's how you measure voltage.This sort of thing.http://en.wikipedia.org/wiki/Clark_cellorhttp://en.wikipedia.org/wiki/Weston_cell
Tommy,Looks like our posts crossed in the night!I found a good ref. on Wiki to the Null Balance Method - it's in my post above.