THE MEASUREMENT OF RESISTANCE 



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together with means for readily inserting them in the circuit, 

 are also required. Three such wires are provided, any one of 

 which may be used at will, and to obtain the effect of a wire of 

 very low resistance, the slide wire proper may be shunted. 

 This is effected by the link seen at the front of the switchboard. 



FIG. 99. Carey Foster bridge. 



Determination of the Resistance per Unit Length of the Slide 

 Wire. To determine R, the resistance per unit length of the slide 

 wire, the process of measurement may be inverted. Let A and 

 B be two coils of nearly equal resistance, so that the balance 



points will fall near the middle of the bridge; only one of the coils 

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