


$(i) R = r$ $(ii)$ Power in $R$ is $\frac{{{E^2}}}{{4R}}$
$(iii)$ Input power $\frac{{{E^2}}}{{2R}}$ $(iv)$Efficiency is $50\%$
$(A)$ The current through $P Q$ is zero.
$(B)$ $I_1=3 A$.
$(C)$ The potential at $S$ is less than that at $Q$.
$(D)$ $I _2=2 A$.