Difficulty: Easy
Correct Answer: Correct
Explanation:
Introduction / Context:Voltage dividers are ubiquitous. However, the ideal unloaded divider assumption breaks once a load is connected. Understanding how loading alters currents and voltages helps in designing dividers with acceptable regulation and selecting buffer stages when needed.
Given Data / Assumptions:
Concept / Approach:The source current equals the sum of currents through all paths tied to the source. Without load, current is I_unloaded = V_in / (R_top + R_bottom). With load, the bottom resistor and R_L form a parallel network, decreasing the effective lower-leg resistance and increasing total divider current. Therefore, the source must deliver more current when a load is attached.
Step-by-Step Solution:
Compute R_lower_eff = R_bottom || R_L.Total divider resistance becomes R_total_loaded = R_top + R_lower_eff.Since R_lower_eff <= R_bottom, R_total_loaded <= R_top + R_bottom.For a fixed V_in, I_loaded = V_in / R_total_loaded ≥ I_unloaded.Verification / Alternative check:Select sample values and calculate currents with and without load; the loaded case always shows higher source current for any finite R_L.
Why Other Options Are Wrong:
Common Pitfalls:Ignoring load interaction when specifying divider resistors; forgetting that heavier loading also drops the output voltage below the ideal unloaded value.
Final Answer:Correct
Discussion & Comments