What are the (a) size and (b) direction (up or down) of current i in Fig, where all resistances are 4.0 Ω and all batteries are ideal and have an emf of 10 V? (Hint: This can be answered using only mental calculation.)
I'm pretty sure KCL/KVL are not the right strategy here. There must exist a clever way to solve this.
My approach 1 : I've tried to find a loop which contains only batteries and the resistor in question, but it seems there is no such trivial loop. Stuck.
My approach 2 : I've simplified series parallel resistors where they give integer equivalent resistances. But the resultant circuit is still not that simple. Stuck. Appreciate any help. Thanks!