---
title: "A real power supply with constant electromotive force \\(\\mathcal{E}\\) and internal resistance \\(r\\) is connected in series with a variable load resistor of resistance \\(R\\). Which of the following best describes the shape of the graph of the power \\(P\\) dissipated by the load resistor as a function of \\(R\\)?"
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url: "https://nerd-notes.com/ubq/118331/"
date_modified: "2026-08-04T08:09:31+00:00"
---

# A real power supply with constant electromotive force \(\mathcal{E}\) and internal resistance \(r\) is connected in series with a variable load resistor of resistance \(R\). Which of the following best describes the shape of the graph of the power \(P\) dissipated by the load resistor as a function of \(R\)?

A real power supply with constant electromotive force \(\mathcal{E}\) and internal resistance \(r\) is connected in series with a variable load resistor of resistance \(R\). Which of the following best describes the shape of the graph of the power \(P\) dissipated by the load resistor as a function of \(R\)?

- **A.** The graph starts at a maximum non-zero value at \(R = 0\) and decreases monotonically toward zero as \(R\) increases.
- **B.** The graph starts at zero at \(R = 0\), increases to a single maximum value at \(R = r\), and then decreases toward zero as \(R\) increases.
- **C.** The graph starts at zero at \(R = 0\) and increases monotonically, approaching a non-zero horizontal asymptote as \(R \to \infty\).
- **D.** The graph is constant and non-zero for all values of \(R\) because the electromotive force \(\mathcal{E}\) is constant.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/118331/*