Current Electricity and Electrical InstrumentHard
Question
Two sources of equal emf are connected to an external resistance R. The internal resistance of the two sources are R1 and R2 = (R2 > R1). If the potential difference across the source having internal resistance R2 is zero, them
Options
A.R = R2 - R1
B.R = R2 = R1 × (R1 + R2)/R2 - R1
C.R = R1 R2 / (R2 - R1)
D.R = R1 R2 / (R1 - R2)
Solution

I =

Pot. differetce across second cell
= V = ε - IR2 = 0
ε =
. R2 = 0R + R1 + R2 - 2R2 = 0
R + R1 - R2 = 0
∴ R = R2 - R1
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