!!n!! identical cells, each of emf !!E!! and internal resistance !!r,!! are joined in series to form a closed circuit.
The potential difference across any one cell is:
(a) !!E !!
(c) !!(n-1)/n E!!
Current in circuit, !!i = (nE)/(nr)= E/r!!
The equivalent circuit of one is shown in figure.
Potential difference across the cell !!= V_A-V_B= -E+ir!!
!!=> V_A-V_B= -E + (E/r)r= -E+E=0!!
Therefore, option (D) is correct .