hi ..this is damn simple ........lets solve it by superposition......superposition technique involves combining 2 situations 2 gether...ok...so we know we need to calc net resistance b/w a and b.....

situation 1 ...connect  positive terminal of d battery to a and ground the other end....

so u see main current is distributed(equally) into 4 branches...

so i/4 in each branch.....

situation 2: connect negative terminal to b and other end is grounded....ok...now u know current leaves frm positive terminl and cums back 2 d negative terminal.........so if u draw  4 urself....u c i/4 current comes back 2 b frm the 4 branches...alrite.....now  superposition !!!!!!!!

u saw i/4 current moving frm a to b...and i/4 current moving frm a to b again in the second situation........add them...u get i/2 current travelling between a and b....

I HOPE U GOT IT................

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