Voltage division in series: a 5.6 kΩ resistor and a 4.7 kΩ resistor are in series. If the voltage across the 5.6 kΩ resistor is 10 V, what is the voltage across the 4.7 kΩ resistor (assume the same series current)?

Electronics Series Circuits Difficulty: Easy
Choose an option
  • A
    8.39 V
  • B
    10 V
  • C
    2.32 V
  • D
    0 V

Answer

Correct Answer: 8.39 V

Explanation

Introduction / Context:In a series network, the same current flows through all resistors. Voltage drops are proportional to resistance values, a principle known as the voltage divider. If one drop is known, the other can be found using ratios without knowing the total source voltage explicitly.

Given Data / Assumptions:

  • Series resistors: R₁ = 5.6 kΩ, R₂ = 4.7 kΩ.
  • Measured V₁ across 5.6 kΩ is 10 V.
  • Ideal components and steady-state DC.

Concept / Approach:

In series: I is common. Therefore V ∝ R. The voltage across the second resistor is V₂ = V₁ * (R₂ / R₁). No need to know the source voltage; the ratio suffices.

Step-by-Step Solution:

Compute ratio R₂ / R₁ = 4.7 / 5.6.Multiply: V₂ = 10 * (4.7 / 5.6) ≈ 10 * 0.8392857 ≈ 8.392857 V.Rounded to two decimals: ≈ 8.39 V.

Verification / Alternative check:

If I is common, V₁/V₂ = R₁/R₂ = 5.6/4.7 ≈ 1.1915; with V₁ = 10 V, V₂ ≈ 10 / 1.1915 ≈ 8.39 V, confirming the result.

Why Other Options Are Wrong:

10 V would imply equal resistances. 2.32 V is far too small for nearly equal-kilo-ohm values. 0 V is impossible with nonzero resistance and nonzero current.

Common Pitfalls:

Using R₁ + R₂ incorrectly; forgetting that the series current is the same and that voltages divide in proportion to resistances.

Final Answer:

8.39 V

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