A group of N cells whose emf varies directly with the internal resistance as per the equation En= 1.5 rNare connected as shown in the figure below. The current I in the circuit is
i=E1+E2+E3+........+En(r1+r2+r3+.........+rn)
=1.5(r1+r2+r3+........+rn)(r1+r2+r3+....+rn) = 1.5A.