---
title: "A direct-current circuit containing an ideal battery, fixed resistors, and an ideal parallel-plate capacitor has been connected for a long time. A voltmeter connected across the terminals of the capacitor indicates a steady, nonzero potential difference, while an ammeter connected in series with the capacitor reads zero. Which of the following provides the correct physical explanation for this observation?"
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url: "https://nerd-notes.com/ubq/124759/"
date_modified: "2026-09-28T14:11:05+00:00"
---

# A direct-current circuit containing an ideal battery, fixed resistors, and an ideal parallel-plate capacitor has been connected for a long time. A voltmeter connected across the terminals of the capacitor indicates a steady, nonzero potential difference, while an ammeter connected in series with the capacitor reads zero. Which of the following provides the correct physical explanation for this observation?

A direct-current circuit containing an ideal battery, fixed resistors, and an ideal parallel-plate capacitor has been connected for a long time. A voltmeter connected across the terminals of the capacitor indicates a steady, nonzero potential difference, while an ammeter connected in series with the capacitor reads zero. Which of the following provides the correct physical explanation for this observation?

![A circuit diagram drawn in black lines on a white background. On the far left, a vertical branch contains a DC voltage source labeled V. A horizontal wire extends to the right from the top terminal and splits into two parallel horizontal paths. The upper horizontal path contains a circle with the letter A inside, connected in series with two parallel vertical line segments representing a capacitor labeled C. Two wire leads branch from either side of the capacitor to a circle with the letter V inside, positioned above the capacitor. The lower horizontal path contains a zigzag symbol representing a resistor labeled R_1. The two paths rejoin at a node on the right, which connects to a second resistor labeled R_2 before returning via a horizontal wire to the bottom terminal of the voltage source. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790604665-Kk4pmb.jpg)

- **A.** The nonzero potential difference requires a continuous flow of charge across the dielectric gap according to Ohm's law, but the resistance of the insulating material is so large that the resulting steady-state current falls below the ammeter's detection threshold.
- **B.** Charges continuously flow onto the positive plate from the higher-potential node and simultaneously flow off the negative plate to the lower-potential node at equal rates, maintaining the voltage while producing a zero net reading on the series ammeter.
- **C.** Because an ideal capacitor cannot store energy without continuous charge replenishment, the zero ammeter reading indicates the capacitor itself is completely uncharged, and the nonzero potential difference is established entirely by current diverted through the internal resistance of the voltmeter.
- **D.** Once the capacitor reaches electrostatic equilibrium, the charge on each plate remains constant so that the time derivative of charge is zero, while the separated static charges sustain an electric field that maintains the potential difference across the insulating gap.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/124759/*