help with question 6 - CHAPTER 24 ELECTROMAGNETIC WAVES...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
CHAPTER 24 ELECTROMAGNETIC WAVES CONCEPTUAL QUESTIONS _____________________________________________________________________________________________ 1. REASONING AND SOLUTION a. The intensity of a wave refers to the power P carried by the wave that passes perpendicularly through a surface in the path of the wave, divided by the area A of the surface. It is given for sound waves by Equation 16.8 and for electromagnetic waves by Equation 24.4. The concept of intensity applies to both sound waves and electromagnetic waves, because both types of wave transfer energy and, therefore, power away from their respective sources. b. In a transverse wave, the particles of the medium vibrate perpendicular to the direction of propagation of the wave. In the case of electromagnetic waves, there are no particle vibrations, but rather the electric and magnetic fields oscillate perpendicular to the direction of propagation of the wave. When a wave is produced or altered so that the vibrations or oscillations take place in a particular direction perpendicular to the wave velocity, the wave is said to be polarized . In a longitudinal wave, the notion of polarization has no meaning, as discussed in Section 24.6 of the text. Therefore, transverse waves can be polarized , while longitudinal waves cannot be polarized . Since sound waves are longitudinal waves, while electromagnetic waves are transverse waves, the concept of polarization applies only to electromagnetic waves. ____________________________________________________________________________________________ 5. REASONING AND SOLUTION The electric field of an electromagnetic wave is related to the magnetic field through the relation E = cB (Equation 24.3). Therefore, if the electric field of a wave decreases in magnitude, the magnetic field will also decrease. This conclusion can also be reached by considering the fact that in an electromagnetic wave propagating through air or vacuum, the electric field and the magnetic field carry equal amounts of energy per unit volume of space. If the electric field of a wave decreases in magnitude, the electric energy per unit volume must decrease. The magnetic energy per unit volume must decrease to the same amount; therefore, the magnitude of the associated magnetic field must also decrease. ____________________________________________________________________________________________ 7. REASONING AND SOLUTION The only real difference between a polarizer and an analyzer is the purpose for which they are used. Both consist of a piece of polarizing material. When the piece of polarizing material is used to produce a desired polarization direction, it is referred to as a polarizer . When the piece of polarizing material is used to change the polarization direction and to adjust the intensity so that the polarization direction of the incident light can be determined, it is referred to as an analyzer . The same piece of polarizing material can be used as the polarizer in one situation and the analyzer in another. ____________________________________________________________________________________________
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chapter 24 Conceptual Questions 1247 10. REASONING AND SOLUTION Light is incident from the left on two pieces of polarizing material, 1 and 2. As part a of the following drawing illustrates, the transmission axis of material 1 is along the vertical direction, while that of material 2 makes an angle of θ with respect to the vertical.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 8

help with question 6 - CHAPTER 24 ELECTROMAGNETIC WAVES...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online