Two cells `A` and `B` with same `e.m.f` of 2 V each and with internal resistances `r_(A)=3.5Omega` and `r_(B)=0.5Omega` are connected in series with an external resistance `R=3Omega` Find the terminal voltages across the two cells.

Explanation

Current through the circuit
`i=e/(R+r) = (2+2)/(3+3.5 + 0.5) = 4/7`
(i) `R= 3Omega, r_(A) = 3.5 Omega, E=2 V`
Terminal voltages A, `V_(A) =E-ir`
`=2-4/7 xx 3.5 = 0` volts
(ii) `r_(B) = 0.5 Omega, R=3 Omega, E=2V`
Terminal voltage at B, `V_(B) =E -ir`
`=2 - 4/7 xx 0.5 =1.714` volts.