Find the current in branch BM in the network shown:

Finding equivalent resistance across CH: $\displaystyle R_{C H}=2 R$ In closed loop ABMNA: $\displaystyle -3 I R-4 I_{1} R+16 E=0$ ………….…………………($\displaystyle 1$) In closed loop BCHMB: $\displaystyle -2 R\left(I-I_{1}\right)-6 E+4 I_{1} R=0$ ……………………………..($\displaystyle 2$) On solving equations ($\displaystyle 1$) and ($\displaystyle 2$): $\displaystyle I_{1}=\frac{25 E}{13 R}$