Resistor value from measurements: if 24 V is applied and the measured current is 10.9 mA, compute the resistance and choose the closest standard value.
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A220 kΩ
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B22 kΩ
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C2.2 kΩ
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D220 Ω
Answer
Correct Answer: 2.2 kΩ
Explanation
Introduction / Context:Finding resistance from voltage and current is a direct application of Ohm’s law. In troubleshooting and lab work, you often infer a component value from in-circuit measurements and then compare against standard E-series values or the nearest option provided.
Given Data / Assumptions:
- Applied voltage V = 24 V.
- Measured current I = 10.9 mA = 0.0109 A.
- Ideal resistive behavior; ignore measurement tolerances for selection.
Concept / Approach:
Use R = V / I. Convert milliampere to ampere to avoid power-of-ten mistakes. After computing, express in convenient SI multiples (kΩ if appropriate) and select the closest option.
Step-by-Step Solution:
R = V / I = 24 / 0.0109 ≈ 2201.83 Ω.Express as kilo-ohms: ≈ 2.20 kΩ.Nearest listed value: 2.2 kΩ.Verification / Alternative check:
Check: I = V / R ≈ 24 / 2200 ≈ 10.9 mA, matching the stated current.
Why Other Options Are Wrong:
220 Ω would imply I ≈ 109 mA; 22 kΩ gives I ≈ 1.09 mA; 220 kΩ gives I ≈ 0.109 mA. None match 10.9 mA.
Common Pitfalls:
Forgetting to convert mA to A; misreading 2.2 kΩ as 220 Ω; rounding too early.
Final Answer:
2.2 kΩ