---
title: "Wire 1 and Wire 2 are fixed parallel to each other at a separation distance of \\(4d\\). Wire 1 carries a current of \\(3I\\) directed into the page, while Wire 2 carries a current of \\(I\\) directed out of the page. Point \\(P\\) lies on the line connecting the two wires at a distance \\(d\\) from Wire 1. Which of the following correctly gives the magnitude of the net magnetic field \\(B_{\\text{net}}\\rangle\\) at point \\(P\\), and the ratio \\(F_1 / F_2\\) of the magnetic force per unit length exerted on Wire 1 to that on Wire 2?"
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url: "https://nerd-notes.com/ubq/117390/"
date_modified: "2026-08-04T06:52:03+00:00"
---

# Wire 1 and Wire 2 are fixed parallel to each other at a separation distance of \(4d\). Wire 1 carries a current of \(3I\) directed into the page, while Wire 2 carries a current of \(I\) directed out of the page. Point \(P\) lies on the line connecting the two wires at a distance \(d\) from Wire 1. Which of the following correctly gives the magnitude of the net magnetic field \(B_{\text{net}}\rangle\) at point \(P\), and the ratio \(F_1 / F_2\) of the magnetic force per unit length exerted on Wire 1 to that on Wire 2?

Wire 1 and Wire 2 are fixed parallel to each other at a separation distance of \(4d\). Wire 1 carries a current of \(3I\) directed into the page, while Wire 2 carries a current of \(I\) directed out of the page. Point \(P\) lies on the line connecting the two wires at a distance \(d\) from Wire 1. Which of the following correctly gives the magnitude of the net magnetic field \(B_{\text{net}}\rangle\) at point \(P\), and the ratio \(F_1 / F_2\) of the magnetic force per unit length exerted on Wire 1 to that on Wire 2?

![A horizontal x-axis shows two long parallel wires perpendicular to the page. Wire 1 is located at position x = 0, represented by a circle with an X inside and labeled '3I into page'. Wire 2 is located at position x = 4d, represented by a circle with a central dot labeled 'I out of page'. Point P is marked on the axis at position x = d with a solid black dot labeled 'P'. Vertical dashed tick lines indicate the positions 0, d, and 4d along the horizontal line connecting the wires. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785826322-hwCeyU.jpg)

- **A.** Net Field \(B_{\text{net}}\): \(\dfrac{5\mu_0 I}{3\pi d}\) \quad | \quad Force Ratio \(F_1/F_2\): \(1\)
- **B.** Net Field \(B_{\text{net}}\): \(\dfrac{5\mu_0 I}{3\pi d}\) \quad | \quad Force Ratio \(F_1/F_2\): \(3\)
- **C.** Net Field \(B_{\text{net}}\): \(\dfrac{4\mu_0 I}{3\pi d}\) \quad | \quad Force Ratio \(F_1/F_2\): \(1\)
- **D.** Net Field \(B_{\text{net}}\): \(\dfrac{4\mu_0 I}{3\pi d}\) \quad | \quad Force Ratio \(F_1/F_2\): \(3\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117390/*