1. True. Internal resistance and lost volt always opposes current ow through the cell”.
2.
Consider two cells in series. Let ε1 , r1 be the emf and internal resistance of first cell. Similarly ε2 , r2 be the emf and internal resistance of second cell. Let I be the current in this circuit.
From the figure, the P.d between A and B
VA – VB = ε1 – 1 ………(1)
Similarly P.d between B and C
VB – VC = ε2 – 1 ……..(2)
Hence, P.d between the terminals A and C
VAC = VA – VC = VA – VB + VB – VC
VAC = [VA – VB] + [VB – VC]
when we substitute eqn. (1) and (2) in the above equation.
VAC = ε1 – Ir1 + ε2 – Ir2
VAC = (ε1 – ε2) – I(r1 + r2)
VAC = εeq – Ireq
where εeq = ε1 + ε2, and req = r1 + r2