---
title: "An experimenter uses a Hall probe to measure the internal magnetic field magnitude \\(B\\) of an air-core toroidal solenoid carrying a constant current of \\(I = 2.0\\text{ A}\\). The measurements are taken at various radial distances \\(r\\) from the central axis of symmetry within the core, and the resulting data are plotted as \\(B\\) versus \\(1/r\\) in the graph shown. Based on the graph, what is the total number of turns \\(N\\) of wire on the toroid?"
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url: "https://nerd-notes.com/ubq/121252/"
date_modified: "2026-08-23T04:59:02+00:00"
---

# An experimenter uses a Hall probe to measure the internal magnetic field magnitude \(B\) of an air-core toroidal solenoid carrying a constant current of \(I = 2.0\text{ A}\). The measurements are taken at various radial distances \(r\) from the central axis of symmetry within the core, and the resulting data are plotted as \(B\) versus \(1/r\) in the graph shown. Based on the graph, what is the total number of turns \(N\) of wire on the toroid?

An experimenter uses a Hall probe to measure the internal magnetic field magnitude \(B\) of an air-core toroidal solenoid carrying a constant current of \(I = 2.0\text{ A}\). The measurements are taken at various radial distances \(r\) from the central axis of symmetry within the core, and the resulting data are plotted as \(B\) versus \(1/r\) in the graph shown. Based on the graph, what is the total number of turns \(N\) of wire on the toroid?

![A 2D Cartesian graph with a horizontal axis labeled 1/r (m^{-1}) spanning from 0 to 30 with major numerical tick marks at 0, 5, 10, 15, 20, 25, and 30. The vertical axis is labeled B (mT) spanning from 0 to 6.0 with major numerical tick marks at 0, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0. Light gray rectangular gridlines align with all major tick marks. A straight solid line begins at the origin (0,0) and extends diagonally upward to the right through the plotted circular data points at (5, 1.0), (10, 2.0), (15, 3.0), (20, 4.0), and (25, 5.0). No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787461141-LPiSuX.jpg)

- **A.** \(125\text{ turns}\)
- **B.** \(250\text{ turns}\)
- **C.** \(500\text{ turns}\)
- **D.** \(1000\text{ turns}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121252/*