Answer: 3R.
- A R/3
- B R
- C 3R
- D R2/3
Correct answer: C. 3R
Explanation: Star to delta: each delta resistance = 3R (each arm in the star contributes to 3 delta arms). Delta resistances = Rstar1 + Rstar2 + Rstar1 x Rstar2/Rstar3 = 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.