Resistance bridge

Here, the unknown resistance is compared with a known resistance using a suitable bridge. Resistance above I Q. can be measured by Wheatstone bridge. Resistance less than I Q can be measured by a Kelvin double bridge, where the lead resistance must also be compensated. 

Three-electrode system — A measurement system with a - potentiostat that uses three electrodes - working, -r counter, and - reference. The systems work in such a way that a desired potential is imposed to the working electrode vs. the reference electrode. The current in the cell flows only between the working and counter electrodes. The reference electrode is not loaded with the current, therefore it preserves its potential even under conditions of high current flowing in the cell. The application of the three-electrode system allows also the elimination of -> salt-bridge resistance and consequently the ohmic potential drop which influences the recorded -> voltammograms. Three-electrode systems do not compensate the entire resistance in the cell. See also - electrochemical cell, -> IRU potential drop. 

No two detonators can be fabricated exactly alike. There is a tolerance on the minimum firing energy as well as on the bridge resistance. These small differences, when related to the time it takes to deliver the firing energy, become very significant, best shown by an example. 

Metal-catalyzed ROP has also been reported for a [2]ferrocenophane with a Ge-Ge bridge, whereas the analogous species with an Si-Si bridge resists polymerization. The presence of weak Cp-Ge bonds may be important in the successful ROP observed in the former case. 

Load Cell—The load cell, in the shape of a cantilever bar, extends 95 mm above its clamp. It is instrumented with two strain gages mounted on each side and wired as a Wheatstone bridge resistance circuit. It has a capacity of 120 N, a limit set to prevent yielding of the aluminum bar at the base. Bar thickness can be increased when more load capacity or load cell stifi iess is needed. Load capacity increases with the square and load cell stiffiiess with the cube of the thickness. 

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