Question

two cells of same emf "E" but different internal resistance 'r​1​' & 'r2' are connected in series to an external resistor 'R' . what should be the value of 'R' so that the potential difference across the terminals of the first cell becomes 0 ?

Answer 1

Answer:

r1 - r2

Correct Answer.

Explanation:

First

terminal potential difference across 1 cell is

V1= E- ir1=0

i = E/r1

Current = 2E/r1+r2+R

Then

Compare Current you Get answer

I have doubt You mentioned in question that Battery is connect with same polarity or opposite polarity

Same polarity -

• Enet= E1 +E2

Opposite Polarity

• Enet= E1-E2

( E1>E2)

Thanks for Reading