.276 



ELECTRICAL MEASUREMENTS 



The resistance K is so adjusted that this total current is kept at 

 0.02 amp. 



In using any form of potentiometer it is absolutely necessary 

 to check the potentiometer current before taking a reading. 



Wolff Potentiometer. Referring to Fig. 157, the battery 

 current from B flows through all the coils marked X 100, then to 



FIG. 157. Wolff potentiometer. 



the lower group marked XO.l where it traverses the coils to the 

 left of the contact D and on to the group XI, traversing the coils 

 to the left of the contact E, thence to the coils to the left of the 

 contact F in the group X 10, and on through all the coils in the 

 group XI, 000. 



