Consider the circuit shown in the figure below:
The voltage 'V' across the 1Ω resistor is
Applying KCL at node (a) , we get ,
Va3+Va3=5−15
6Va=−90 ⇒ Va=−15V
∵The current through 1Ω resistor is Va3=−153=−5A
∴The voltage across 1Ω resistor is−5V