Current from voltage across a resistor — apply Ohm’s law: The voltage across a 5 kΩ resistor is 25 V. The current through the resistor is ______.
Electronics
Ohm's Law
Difficulty: Easy
Choose an option
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A200 mA
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B125 mA
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C75 mA
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D5 mA
Answer
Correct Answer: 5 mA
Explanation
Introduction / Context:Given the voltage across and resistance of a component, Ohm’s law provides the current. Careful unit handling (kΩ) avoids common errors in the milliampere range.
Given Data / Assumptions:
- V = 25 V.
- R = 5 kΩ = 5000 Ω.
- Linear resistor, steady state.
Concept / Approach:Use I = V / R. Convert kilo-ohms to ohms before dividing to get amperes, then express the result in milliamperes if convenient for readability.
Step-by-Step Solution:
I = V / R = 25 / 5000 A.Compute: 25 / 5000 = 0.005 A.Convert: 0.005 A = 5 mA.Therefore, current is 5 mA.Verification / Alternative check:Check voltage drop: V = I * R = 0.005 * 5000 = 25 V, consistent.
Why Other Options Are Wrong:
200 mA / 125 mA / 75 mA: far too large for 25 V across 5 kΩ; would require much lower resistance values.Common Pitfalls:Forgetting to convert kΩ to Ω, leading to answers 1000× too large or small.
Final Answer:5 mA