Answer: 3R.
- A R/3
- B R
- C 3R
- D R<sup>2</sup>/3
Correct answer: C. 3R
Explanation: Star to delta: each delta resistance = 3R (each arm in the star contributes to 3 delta arms). Delta resistances = R<sub>star1</sub> + R<sub>star2</sub> + R<sub>star1</sub> x R<sub>star2</sub>/R<sub>star3</sub> = 3R for equal stars.
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.