Question

Pls see the attached file and find the effective resistance between A and C

Answer 1

see the answer is simple
if you observe carefully, the upper part of the circuit forms a wheatstone bridge
http://en.wikipedia.org/wiki/Wheatstone_bridge
so the resistance of 1 ohm can be removed as shown in the below diagram and we are left with a simple parallel connection of three resistors of value 2 ohm, 2 ohm and 1 ohm
so the equivalent resistance between A and C becomes
R = 0.5 ohm

Answer 2

That's correct.

Answer 3

thanks n medal given...☺

Answer 4

I always give medal if someone draws a good illustration :-).

The problem is also possible to solve with Delta-Star-transform:
http://en.wikipedia.org/wiki/Y-%CE%94_transform

but your way is more elegant and easier.