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# Under what conditions, can the current passing through the resistance R be increased? r1 and r2 are the internal resistances of the two batteries.

$\begin {array} {1 1} (A)\;E_2r_1 > E_1(R + r_2) & \quad (B)\; E_1r_2 > E_2(R + r_1) \\ (C)\;E_2r_2 < E_1(R + r_2) & \quad (D)\;E_1r_1 > E_2(R + r_1) \end {array}$

Current before E2 is shorted $= i_1 = \large\frac{E1+E2}{R+r1+r2}$
Current after E2 is shorted $= i_2 = \large\frac{E1}{R+r1}$
$i_2 > i_1,$ this gives $E_1r_2 > E_2(R + r_1)$
Ans : (B)
edited Mar 14, 2014