A wire of resistance 20ohm is bended to form a closed square. What is the resistance across the diagonal of the square?
each of the four sides of the square is 5 Ω
diagonally, there are two parallel paths of two 5 Ω resistances in series
each path is 10 Ω (5 + 5), and the two paths in parallel results in a net resistance of 5 Ω