---
title: "A circuit consists of an ideal DC voltage source of potential difference \\(\\Delta V_0\\), a fixed resistor of resistance \\(R_0\\), and a variable resistor of resistance \\(R_x\\) connected in series. The resistance \\(R_x\\) is initially set to zero and is then gradually increased. Which of the following graphs best represents the current \\(I\\) in the circuit as a function of the variable resistance \\(R_x\\)?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/117271/"
date_modified: "2026-08-04T06:45:10+00:00"
---

# A circuit consists of an ideal DC voltage source of potential difference \(\Delta V_0\), a fixed resistor of resistance \(R_0\), and a variable resistor of resistance \(R_x\) connected in series. The resistance \(R_x\) is initially set to zero and is then gradually increased. Which of the following graphs best represents the current \(I\) in the circuit as a function of the variable resistance \(R_x\)?

A circuit consists of an ideal DC voltage source of potential difference \(\Delta V_0\), a fixed resistor of resistance \(R_0\), and a variable resistor of resistance \(R_x\) connected in series. The resistance \(R_x\) is initially set to zero and is then gradually increased. Which of the following graphs best represents the current \(I\) in the circuit as a function of the variable resistance \(R_x\)?

![A schematic circuit diagram of a single closed loop. On the left vertical branch, a DC voltage source is drawn with a long parallel line and a short thick line, labeled \(\Delta V_0\). On the top horizontal branch, a zig-zag resistor symbol is drawn and labeled \(R_0\). On the right vertical branch, a second zig-zag resistor symbol is drawn with a diagonal arrow pointing through its center, labeled \(R_x\). Solid black lines connect all components in a continuous rectangular loop. No other components, text, or labels appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-circuit-1-1785825909-05Ovgq.jpg)

- **A.** Graph A
- **B.** Graph B
- **C.** Graph C
- **D.** Graph D

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117271/*