The equivalent circuit is shown in figure.
Effective resistance `R_(p)` between A and B will be
`1/R_(p) = 1/3 + 1/14 +1/6 +1/6 = 31/42`
or `R_(p) = 42/31 Omega`
Current from the cell,
`I = epsilon/(R_(p) +r) = 1.8/(42/31+ 2/3) = 0.89A`
Potential diff. between A and B,
`V_(A) - V_(B) = I R_(p) = 0.89 xx 42/31 = 1.21 V`
Current in `3 Omega` resistance `= 1.21/3 = 0.4A`
Power dissipated in the whole circuit (including the cell)is
`P = I^(2) (R + r) = (0.89)^(2) (42/31 + 2/3)`
`= 1.6` watt
