Question

Twelve 6 ohm resistors are used to form an edge of a cube. The resistance between two diagonally opposite corner of the cube (in ohm) is ________

(a) 5/6

(b) 6/5

(c) 5

(d) 6

This question was posed to me in quiz.

My question is based upon Basic Concepts in division EDC Overview of Electronic Devices & Circuits

Answer 1

Correct choice is (c) 5

The best explanation: The current I will be distributed to the cube branches symmetrically.

 Connecting a voltage source Vab across the terminals and applying kvl in the outer loop, we have

=> -Vab + (i/3+i/6+i/3)*R = 0    (where R is given as 6ohm)

=> Vab = 5i

=> Req=Vab/i, which gives Req = 5ohm.