Answer: 5/6 ohm.
- A 5/6 ohm
- B 3/4 ohm
- C 7/12 ohm
- D 12/7 ohm
Correct answer: A. 5/6 ohm
Explanation: For a resistor cube between opposite corners: by symmetry and Kirchhoff, equivalent resistance = 5R/6 = 5/6 ohm.
In series, the same current flows through both resistors; in parallel, the current splits between branches and the voltage across each resistor is the same.
Concept context
Ohm's law, resistors, Kirchhoff's laws, Wheatstone bridge, and cells.