---
title: "An ideal LC circuit consists of an inductor connected to a fully charged capacitor. At time t = 0, a switch is closed, allowing charge and current to oscillate. The accompanying graph displays the electric energy U_E stored in the capacitor (solid line) and the magnetic energy U_B stored in the inductor (dashed line) as functions of time t.  Which of the following statements correctly identifies the fundamental frequency of the circuit’s current oscillation and the state of the circuit at one of the labeled times?"
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/125000/"
date_modified: "2026-09-28T14:13:05+00:00"
---

# An ideal LC circuit consists of an inductor connected to a fully charged capacitor. At time t = 0, a switch is closed, allowing charge and current to oscillate. The accompanying graph displays the electric energy U_E stored in the capacitor (solid line) and the magnetic energy U_B stored in the inductor (dashed line) as functions of time t.

Which of the following statements correctly identifies the fundamental frequency of the circuit’s current oscillation and the state of the circuit at one of the labeled times?

An ideal LC circuit consists of an inductor connected to a fully charged capacitor. At time t = 0, a switch is closed, allowing charge and current to oscillate. The accompanying graph displays the electric energy U_E stored in the capacitor (solid line) and the magnetic energy U_B stored in the inductor (dashed line) as functions of time t.

Which of the following statements correctly identifies the fundamental frequency of the circuit's current oscillation and the state of the circuit at one of the labeled times?

![A graph with a horizontal time axis labeled t (ms) marked from 0 to 4.0 with major tick marks at 0, 1.0, 2.0, 3.0, and 4.0, and minor ticks at 0.5, 1.5, 2.5, and 3.5. The vertical axis is labeled U (mJ) with tick marks at 0, 0.5 U_0, and U_0. A solid curve representing U_E starts at the vertical coordinate U_0 at t = 0, curves smoothly down to touch 0 at t = 1.0, rises to a peak at U_0 at t = 2.0, falls to 0 at t = 3.0, and returns to U_0 at t = 4.0. A dashed curve representing U_B starts at 0 at t = 0, rises to a peak at U_0 at t = 1.0, falls to 0 at t = 2.0, rises to U_0 at t = 3.0, and falls to 0 at t = 4.0. The two curves intersect exactly at vertical height 0.5 U_0 at times t = 0.5, 1.5, 2.5, and 3.5. A small legend in the upper-right corner shows a solid line labeled U_E and a dashed line labeled U_B. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-graph-1-1790604784-wjSKAh.jpg)

- **A.** The fundamental frequency of the oscillating current is \(500\text{ Hz}\), and the current in the inductor is zero at \(t = 1.0\text{ ms}\).
- **B.** The fundamental frequency of the oscillating current is \(500\text{ Hz}\), and the magnitude of the current at \(t = 0.5\text{ ms}\) is half of its maximum value.
- **C.** The fundamental frequency of the oscillating current is \(250\text{ Hz}\), and the current in the inductor reaches its maximum magnitude at \(t = 1.0\text{ ms}\).
- **D.** The fundamental frequency of the oscillating current is \(250\text{ Hz}\), and the magnitude of the induced emf across the inductor is at a maximum at \(t = 1.0\text{ ms}\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/125000/*