The expression which gives the relation between the voltage and current is given by, V=IR For the potential drop of 2V takes place across the parallel branch AB the expression is calculated as, V=IR 2=I32 I3=1A The voltage across the branch AB is calculated as, VAB=5−I3R2 2=5−1×R2 R2=3Ω The voltage V2 across R2 is calculated as, v2=−I3R2 =−3×1 =−3V