Two resistors of 60 Ω and 20 Ω are connected in parallel. What is their combined resistance?
Answer and explanation
Correct answer: B. 15 Ω
- Step 1: For parallel resistors 1/R = 1/R₁ + 1/R₂, so R = R₁R₂/(R₁ + R₂). Step 2. R = 60 × 20 ÷ 80 = 15 Ω. Answer: 15 Ω. Why not the others: 80 Ω is what you get if you add them as in series. 40 Ω is what you get if you take the average. 1200 Ω is what you get if you multiply them.
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