For the two cells having same EMF E and internal resistance r, the current passing through the external resistor 6 is same when both the cells are connected either in parallel or in series. The value of internal resistance r is .
(2) 6
In series, Eeq = 2E and req = 2r, so Is = 2E6 + 2r.
In parallel, Eeq = E and req = r2, so Ip = E6 + r2 = 2E12 + r.
Is = Ip,
6 + 2r = 12 + r
r = 6
Answer: (2)
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