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title: "A student designs a circuit to determine the resistance \\(R\\) of an unknown resistor. As shown in the diagram, a non-ideal voltmeter with finite internal resistance \\(R_V\\) is connected in parallel across the resistor, and a non-ideal ammeter with nonzero internal resistance \\(R_A\\) is connected in series with the parallel combination. The ammeter records a current \\(I_{\\text{meas}}\\) and the voltmeter records a potential difference \\(V_{\\text{meas}}\\), from which the experimental resistance is calculated as \\(R_{\\text{exp}} = \\dfrac{V_{\\text{meas}}}{I_{\\text{meas}}}\\). How does the measured current \\(I_{\\text{meas}}\\) compare to the actual current \\(I_R\\) passing through the resistor during the measurement, and how does the calculated resistance \\(R_{\\text{exp}}\\) compare to the true resistance \\(R\\)?"
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url: "https://nerd-notes.com/ubq/121573/"
date_modified: "2026-08-23T05:24:06+00:00"
---

# A student designs a circuit to determine the resistance \(R\) of an unknown resistor. As shown in the diagram, a non-ideal voltmeter with finite internal resistance \(R_V\) is connected in parallel across the resistor, and a non-ideal ammeter with nonzero internal resistance \(R_A\) is connected in series with the parallel combination. The ammeter records a current \(I_{\text{meas}}\) and the voltmeter records a potential difference \(V_{\text{meas}}\), from which the experimental resistance is calculated as \(R_{\text{exp}} = \dfrac{V_{\text{meas}}}{I_{\text{meas}}}\). How does the measured current \(I_{\text{meas}}\) compare to the actual current \(I_R\) passing through the resistor during the measurement, and how does the calculated resistance \(R_{\text{exp}}\) compare to the true resistance \(R\)?

A student designs a circuit to determine the resistance \(R\) of an unknown resistor. As shown in the diagram, a non-ideal voltmeter with finite internal resistance \(R_V\) is connected in parallel across the resistor, and a non-ideal ammeter with nonzero internal resistance \(R_A\) is connected in series with the parallel combination. The ammeter records a current \(I_{\text{meas}}\) and the voltmeter records a potential difference \(V_{\text{meas}}\), from which the experimental resistance is calculated as \(R_{\text{exp}} = \dfrac{V_{\text{meas}}}{I_{\text{meas}}}\). How does the measured current \(I_{\text{meas}}\) compare to the actual current \(I_R\) passing through the resistor during the measurement, and how does the calculated resistance \(R_{\text{exp}}\) compare to the true resistance \(R\)?

![A rectangular circuit schematic in black line art on a white background. On the left vertical segment is a DC voltage source labeled \(\mathcal{E}\), depicted by a longer horizontal line above a shorter parallel thick line. From the top of the source, a wire extends upward, turns right 90 degrees, and passes horizontally through an ammeter, shown as a circle containing the capital letter A. Past the ammeter, the wire reaches a T-junction that splits into two vertical parallel branches. The left branch contains a rectangular zig-zag resistor labeled R. The right branch contains a circle with the capital letter V representing a voltmeter. Below these two elements, the two vertical branches rejoin at a bottom T-junction. A wire extends from this bottom junction, turns left 90 degrees, and connects back to the bottom terminal of the voltage source. No other labels, lines, text, or components appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-circuit-1-1787462646-CUakHE.jpg)

- **A.** \(I_{\text{meas}} < I_R\) ; \(R_{\text{exp}} > R\)
- **B.** \(I_{\text{meas}} > I_R\) ; \(R_{\text{exp}} > R\)
- **C.** \(I_{\text{meas}} > I_R\) ; \(R_{\text{exp}} < R\)
- **D.** \(I_{\text{meas}} < I_R\) ; \(R_{\text{exp}} < R\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121573/*