(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Provided that the input resistance of the DMM is

much larger than the resistance values in the circuit to

which it is connected, the DMM will not draw a

significant current. Estimate the input resistance of the

DMM by connecting the 10 M resistor supplied in

series with it and noting the voltage reading when

this series combination is connected to your DC black

box. Explain clearly the logic of doing this.

Basically I have a simple circuit with a DC black box which is a box with a 1.5V battery and three resistors (1 in series and 2 in parallel) and I have a digital multimeter that I have to estimate its internal resistance by connecting a 10 MΩ resistor to the circuit in series with the multimeter. I can't really think of why connecting such a large resistor would help determine the internal resistance.

3. The attempt at a solution

I haven't been able to come up with an answer because first I need to understand the role of the 10 MΩ resistor.

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# Homework Help: Internal resistance of a digital multimeter

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