Talk:Four-terminal sensing

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What's up with that drawing??[edit]

What is U? What is a circle with a line through it mean? Is this some Euro-stuff? I have been electronics for 30+ years and have never seen these symbols. Without any text explaining the figure (or figure numbers for that matter) the drawing is pretty much worthless. Leaves you to guess what Ri means and which is the force and sensing nodes. How about junking this figure and using the one below it with some text to explain what is going on. I actually know how 4 point Kelvin sensing works but if I were a youngster trying to figure it out this article would not teach me much. — Preceding unsigned comment added by (talk) 16:20, 20 November 2012 (UTC)

Totally agree. To make the drawing accessible / understandable to a wider audience, suggest using simpler symbols for current and voltage. Stop trying to be "fancy". Simple is best. — Preceding unsigned comment added by (talk) 02:28, 6 August 2013 (UTC)

No longer an orphan article[edit]

I have added two links in related articles, so I have removed the {{linkless|September 2006}} tag. DFH 16:45, 1 December 2006 (UTC)

Rename ?[edit]

Anyone else agree that we could well rename this article as Kelvin sensing ? DFH 16:47, 1 December 2006 (UTC)

I'm curious as to why? I am not an expert on this but when the technical manuals that Agilent releases refer to two-, three-, four-terminal sensing when they talk about impedance analyzing. It might just be for simplicity's sake. I had actually never heard of Kelvin sensing until I read it on Wikipedia. -- Bubbachuck 08:08, 7 December 2006 (UTC)
Kelvin sensing is the standard term in the realm of [power] semiconductor testing. DFH 19:31, 7 December 2006 (UTC)
OK, you seem to be more knowledgeable, so if you think its a good name change go ahead. -- Bubbachuck 00:11, 12 December 2006 (UTC)

Merge this with the "Kelvin bridge" article? —Preceding unsigned comment added by (talk) 11:14, 16 December 2009 (UTC)

Don't merge it; this article is meaningful quite separate from Kelvin bridges. As for terminology, I've heard both. The current title is fine. It's easy to add a redirect so the other title also works. Paul Koning (talk) 18:09, 23 March 2011 (UTC)

In the Heat Transfer field, I hear "Four Point Probe" most often, "Four Terminal" second, and had never heard the measurement called a Kelvin Bridge before I came to this article. — Preceding unsigned comment added by (talk) 19:04, 8 April 2012 (UTC)

Section rescued from resistivity[edit]

A writer called Vessels42 went to some trouble to write a new section on this topic in the Resistivity article, so I rescued it in case I decide to merge it in to this article later:

==Four point resistivity measurement==
Schematic of a four-point resistivity measurement.
When the resistivity of a sample is measured by simply attaching two wire leads and passing a current through the sample at a known voltage, one inadvertently measures the resistance of the wire leads. For small resistivity measurements and systems where there is a strong temperature dependence, such as superconductors, the resistance of the wires (known as contact resisitance) can completely dominate the measurement. In this situation it is neccessary to use a four-point resistivity probe.
For this measurement, shown at right, a constant current flows through the sample across leads 1 and 4, with an ammeter in series to measure the current. If the sample has a nonzero resistivity, there will be a voltage drop along the length, including between leads 2 and 3, where a voltmeter has been placed. The resistance of the sample is given by the measured voltage divided by the measured current (Ohm's law). The high impedance of the voltmeter assures that little current flows through wires 2 and 3, and thus the measured resistance is attributed only to the sample between those wires, eliminating contact resistance.


Resistive element (blue) measured with separate force (red) and sense (green) connections.
Thanks for the illustration! I used it to replace the less clear one relegated here. (talk) 07:08, 30 June 2009 (UTC)

got Dutch?[edit]

How come the graphic has dutch words? Anybody want to photoshop the words into english? ROOD = red Wit = White I havn't a clue what the other words mean eximo (talk) 18:52, 23 February 2010 (UTC)

Ordering of the wires?[edit]

I don't understand the claim that the sense wires must be the inner wires. If anything, I would argue they must be the outer wires. Reason: if "inner" means they attach to the resistor inbound from the current terminals, then the sense terminals are picking up the voltage across a subset of the whole resistor, so the reading would be in error (too low). Conversely, if you attach the sense points outbound from the current terminals, you have some resistor in series with the sense wires. But since the sense wire current is nearly zero (precisely zero, in the case of a bridge) that extra resistance does not have any effect. Paul Koning (talk) 18:12, 23 March 2011 (UTC)

We don't need to argue - we just need to cite a reference. What do the authorities say? --Wtshymanski (talk) 18:47, 23 March 2011 (UTC)