Book cover for Physics

Physics

John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler

ISBN #9781118486894

10th Edition

2,562 Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

This section provides a comprehensive exploration of electromagnetic waves, highlighting that they consist of mutually perpendicular and oscillating electric and magnetic fields which propagate at the speed of light in a vacuum. Key topics include the electromagnetic spectrum, the energy and intensity of waves, and the methods for calculating various related quantities. The chapter also delves into the Doppler effect for electromagnetic waves, emphasizing the differences from acoustic waves, and explains polarization phenomena and applications such as Malus’ law, which is fundamental in technologies ranging from LCD displays and sunglasses to advanced imaging systems.

Learning Objectives

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Key Concepts

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Example Problems

Example 1

The team monitoring a space probe exploring the outer solar system finds that radio transmissions from the probe take 2.53 hours to reach earth. How distant (in meters) is the probe?

Example 2

(a) Neil A. Armstrong was the first person to walk on the moon. The distance between the earth and the moon is $3.85 \times 10^{8} \mathrm{m}$. Find the time it took for his voice to reach the earth via radio waves. (b) Someday a person will walk on Mars, which is $5.6 \times 10^{10} \mathrm{m}$ from the earth at the point of closest approach. Determine the minimum time that will be required for a message from Mars to reach the earth via radio waves.

Example 3

In astronomy, distances are often expressed in light-years. One light-year is the distance traveled by light in one year. The distance to Alpha Centauri, the closest star other than our own sun that can be seen by the naked eye, is 4.3 light-years. Express this distance in meters.

Example 4

FM radio stations use radio waves with frequencies from 88.0 to $108 \mathrm{MHz}$ to broadcast their signals. Assuming that the inductance in Figure 24.4 has a value of $6.00 \times 10^{-7} \mathrm{H},$ determine the range of capacitance values that are needed so the antenna can pick up all the radio waves broadcasted by FM stations.

Example 5

In a traveling electromagnetic wave, the electric field is represented mathematically as $$ E=E_{0} \sin \left[\left(1.5 \times 10^{10} \mathrm{s}^{-1}\right) t-\left(5.0 \times 10^{1} \mathrm{m}^{-1}\right) x\right] $$ where $E_{0}$ is the maximum field strength. This equation is an adaptation of Equation $16.3 .$ (a) What is the frequency of the wave? (b) This wave and the wave that results from its reflection can form a standing wave, in a way similar to that in which standing waves can arise on a string (see Section 17.5 ). What is the separation between adjacent nodes in the standing wave?
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Common Mistakes

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