O Levels Physics (5054)•5054/11/M/J/22
Explanation
Equivalent resistance decreases with more parallel paths Steps:
- Identify configurations: Assume A is all series (R_total = 300Ω), B is two parallel then series with one ((50Ω + 100Ω) = 150Ω), C is all parallel (R_total = 100Ω/3 ≈ 33.3Ω), D is one parallel pair in series with the third (150Ω).
- Apply series formula: R_series = R1 + R2 + R3.
- Apply parallel formula: 1/R_parallel = 1/R1 + 1/R2 + 1/R3.
- Compare values: Smallest is C's 33.3Ω.
Why C is correct:
- All three resistors in parallel minimize resistance per the formula 1/R_eq = Σ(1/R_i), yielding ~33.3Ω.
Why the others are wrong:
- A: All series maximizes resistance at 300Ω.
- B: Partial parallel-series combo gives 150Ω, higher than full parallel.
- D: Similar partial combo yields 150Ω, not minimal.
Final answer: C
Topic: Series and parallel circuits
Practice more O Levels Physics (5054) questions on mMCQ.me