hello! I have some difficulty in nodal analysis I want to know basically how to apply KCL and Ohm's Law to find the equations few branches meet in a node I know that KCL means that sum of currents that enter are equal to the sum of currents are leaving the node the problem is that I may not know the directions of the currents 1) do I choose them arbitrarily? 2) after choosing them arbitrarily, how do I find the voltage difference across a branch? V1-V2 or V2-V1 ? thanks!