---
title: "An isotropic transmitter emits electromagnetic radio waves uniformly in all directions through space. A detector measures the wave intensity \\(I\\) at various distances \\(r\\) from the source. A graph of the measured intensity \\(I\\) as a function of \\(\\dfrac{1}{r^2}\\) is shown. Based on the graph, what is the total power emitted by the transmitter?"
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/117442/"
date_modified: "2026-08-04T06:52:10+00:00"
---

# An isotropic transmitter emits electromagnetic radio waves uniformly in all directions through space. A detector measures the wave intensity \(I\) at various distances \(r\) from the source. A graph of the measured intensity \(I\) as a function of \(\dfrac{1}{r^2}\) is shown. Based on the graph, what is the total power emitted by the transmitter?

An isotropic transmitter emits electromagnetic radio waves uniformly in all directions through space. A detector measures the wave intensity \(I\) at various distances \(r\) from the source. A graph of the measured intensity \(I\) as a function of \(\dfrac{1}{r^2}\) is shown. Based on the graph, what is the total power emitted by the transmitter?

![A Cartesian graph with a horizontal axis labeled 1/r^2 (m^{-2}) and a vertical axis labeled Intensity I (W/m^2). The horizontal axis ranges from 0 to 0.25 with major grid lines and tick marks every 0.05, labeled 0, 0.05, 0.10, 0.15, 0.20, and 0.25. The vertical axis ranges from 0 to 250 with major grid lines and tick marks every 50, labeled 0, 50, 100, 150, 200, and 250. A solid black linear trend line starts at the origin (0, 0) and extends upward to the right, passing precisely through grid intersections at (0.05, 50), (0.10, 100), (0.15, 150), and (0.20, 200), ending at (0.25, 250). Dark circular data points are plotted at these four grid intersections. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785826330-7RpSpz.jpg)

- **A.** \(8.0 \times 10^1 \text{ W}\)
- **B.** \(1.0 \times 10^3 \text{ W}\)
- **C.** \(3.1 \times 10^3 \text{ W}\)
- **D.** \(1.3 \times 10^4 \text{ W}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117442/*