A 6 volt battery of negligible internal resistance is connected across a potentiometer wire is AB of length 100 cm and uniform area of cross-section. The posistive terminal of another battery of emf 4 V and internal resistance `1 Omega` is joined to the point A as shown in figure. If we take potential at B to be zero, (a) What are the potentials at points A and C. (b) At which point D of the potentiometer C? ( C) If the points C and D are connected by a wire, What will be the current through itgt (d) if the 4 V battery is replaced by 7.5 V battery, what would be the answers of parts (a) and (b)?

Explanation

(a) `V_A = 6 V, V_C = 6 - 4 = 2 V`
(b)
No deflection in galvanometer, `V_C = V_D`
`(6)/(100) x = 4 rArr x = (200)/(3) = 66.7 cm`.
( c) Zero
(d) `V_A = 6 V, V_C = -1.5 V`
There is no such point like `D`.