---
title: "A primary coil connected in series with a battery, an open switch, and a resistor is fixed in place. A lightweight, closed conducting secondary coil is aligned coaxially with the primary coil on a frictionless horizontal support and is free to move. The switch is closed, kept closed until a steady current is established, and then reopened.  Which of the following correctly describes the magnetic force exerted on the secondary coil and the induced current in the secondary coil during each of these three stages?  | | Force Immediately After Closing | Current in Steady State | Force Immediately After Reopening | | :— | :— | :— | :— |"
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/123325/"
date_modified: "2026-09-28T11:58:09+00:00"
---

# A primary coil connected in series with a battery, an open switch, and a resistor is fixed in place. A lightweight, closed conducting secondary coil is aligned coaxially with the primary coil on a frictionless horizontal support and is free to move. The switch is closed, kept closed until a steady current is established, and then reopened.

Which of the following correctly describes the magnetic force exerted on the secondary coil and the induced current in the secondary coil during each of these three stages?

| | Force Immediately After Closing | Current in Steady State | Force Immediately After Reopening |
| :— | :— | :— | :— |

A primary coil connected in series with a battery, an open switch, and a resistor is fixed in place. A lightweight, closed conducting secondary coil is aligned coaxially with the primary coil on a frictionless horizontal support and is free to move. The switch is closed, kept closed until a steady current is established, and then reopened.

Which of the following correctly describes the magnetic force exerted on the secondary coil and the induced current in the secondary coil during each of these three stages?

| | Force Immediately After Closing | Current in Steady State | Force Immediately After Reopening |
| :--- | :--- | :--- | :--- |

![A schematic diagram showing two coaxial circular coils sharing a horizontal dashed central axis. On the left, a multi-loop cylindrical coil labeled primary coil is wired into a series circuit containing an open switch labeled S, a resistor labeled R, and a battery labeled \varepsilon. On the right, along the same horizontal dashed line, a closed single-loop circular ring labeled secondary coil rests on a flat horizontal support line. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790596689-30OQfB.jpg)

- **A.** | Directed toward primary | Nonzero | Directed away from primary |
- **B.** | Directed away from primary | Nonzero | Directed toward primary |
- **C.** | Directed toward primary | Zero | Directed away from primary |
- **D.** | Directed away from primary | Zero | Directed toward primary |

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123325/*