Four resistance 40Ω,60Ω,90Ω, and 110Ω make the arms of a quadrilateral ABCD. Across AC is a battery of emf 40 V and internal resistance negligible. The potential difference across BD in V is ____
Answer: 2
Solution
With the 40V battery across the diagonal AC, the current splits between the two arms. Along A-B-C the resistance is 40+60=100Ω, giving i1=10040=0.4A, while along A-D-C it is 90+110=200Ω, giving i2=20040=0.2A. Then VB=VA−40i1=VA−16V and VD=VA−90i2=VA−18V, so the potential difference across BD is VB−VD=2V.