Figure 27-61
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Homework 27.55
In Fig. 27.61, Rs is to be adjusted
in value by moving the sliding contact across it until
points a and b are brought to the same potential.
(One tests for this condition by momentarily connecting
a sensitive ammeter between a and b; if these points
are at the same potential, the ammeter will not deflect.)
Show that when this adjustment is made, the following
relation holds: Rx = Rs R2
/R1. An unknown resistance (Rx)
can be measured in terms of a standard (Rs) using this device ,
which is called a Wheatstone bridge,erms of a standard (Rs)