A resistive divider is built from a steady supply

PHYSICS · Multi-part · Fermi University Physics · Electronics, Instrumentation & Communication · Circuit foundations and passive networks · Sensors, detectors and experimental instrumentation

Electronics for Measurement, Ch The resistive network: two laws, one equivalent and the loading error

Problem

A resistive divider is built from a 10.0 V10.0\,\mathrm{V} steady supply, a resistor R1=2.2 kΩR_1 = 2.2\,\mathrm{k\Omega} from the supply's positive terminal to a node, and a resistor R2=4.7 kΩR_2 = 4.7\,\mathrm{k\Omega} from that node to ground. Before connecting anything to the node, a multimeter with input resistance Rm=10 kΩR_{\rm m} = 10\,\mathrm{k\Omega} is about to be placed between the node and ground. ((a)) State the voltage the node would show with nothing connected to it. ((b)) Predict, without drawing the meter into the circuit and re-solving from scratch, the voltage the meter will read once it is connected. ((c)) Give the percentage by which this reading falls short of the unloaded value.

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