Difficulty: Easy
Correct Answer: Correct
Explanation:
Introduction / Context:A voltage divider provides a reference voltage but is sensitive to loading. When an external load is connected, the output falls due to the divider's Thevenin resistance. This question compares two loads (6 kΩ versus 5 kΩ) to evaluate which causes less output sag.
Given Data / Assumptions:
Concept / Approach:The loaded output is V_out = V_oc * (R_L / (R_th + R_L)). For fixed R_th and V_oc, a larger R_L yields a larger fraction and therefore a higher V_out (less droop). Hence, 6 kΩ (larger than 5 kΩ) loads the divider less and produces a smaller decrease from the open-circuit value.
Step-by-Step Solution:
Model the divider and its source as a Thevenin equivalent: V_oc in series with R_th.For R_L = 6 kΩ: V6 = V_oc * (6k / (R_th + 6k)).For R_L = 5 kΩ: V5 = V_oc * (5k / (R_th + 5k)).Compare: since 6k / (R_th + 6k) > 5k / (R_th + 5k) for R_th ≥ 0, V6 > V5, so the 6 kΩ load causes a smaller drop.Verification / Alternative check:Pick R_th = 2 kΩ and V_oc = 10 V. With 6 kΩ: V_out ≈ 10 * (6000/8000) = 7.5 V. With 5 kΩ: V_out ≈ 10 * (5000/7000) ≈ 7.14 V. The 6 kΩ case has less sag, matching the rule of thumb to use a load at least 10× the source resistance.
Why Other Options Are Wrong:
Common Pitfalls:Ignoring the source/ divider's Thevenin resistance, or assuming that higher-ohm loads always draw "more" voltage drop in the source. In reality, higher-ohm loads draw less current and thus cause less droop.
Final Answer:Correct — a 6 kΩ load produces a smaller output decrease than a 5 kΩ load on the same divider.
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