Current Electricity and Electrical InstrumentHard
Question
In the fig. the potentiometer wire AB of length L & resistance 9 r is joined to the cell D of e.m.f. ε & internal resistance r. The cell C′s e.m.f. is ε/2 and its internal resistance is 2r. The galvanometer G will show no deflection when the length AJ is:
Options
A.4L/9
B.5L/9
C.7L/18
D.11L/18
Solution
Current in primary circuit. I = 
Potential drop across length AB = VAB = I.R
VAB =
= 
x =
For balance point
= x l = 
l. l = 
L
Potential drop across length AB = VAB = I.R
VAB =
= x =
For balance point
= x l = l. l = LCreate a free account to view solution
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