Review Guide:   Waves – Chapter 11

 11.1

1. Define:  wave
2. Waves that require a medium through which to travel are called:
3. Give one major exception to the previous type of waves:
4. The changing of electric and magnetic fields as they travel is:
5. Mechanical Energy:  the kinetic and potential energy of large-scale objects in a system
6. Wave Motion transfers only energy, not matter.  Even though mechanical waves are transferred by the motion of matter, no matter itself is transferred.
7. Mechanical waves spread out through the medium evenly and spherically from the source if the source is open to the medium in all directions (speaker sound waves).
8. Most waves are created by:
9. Electromagnetic waves may be caused by vibrating:
10. Describe potential and kinetic energy in the following system:  a heavy weight is suspended from a spring which is attached to a support.  The weight is pulled downward (define P.E. and K.E., then describe the oscillation of the mass from its resting position as it is pulled downward).
11. Sketch an X versus Y axes.  The X-axis should be labeled “elapsed time” and the Y-axis labeled “displacement”.  Zero on the X-axis represents the resting position of the mass.  Graph the displacement of the weight over time as it moves up and down.
12. Define damped harmonic motion.
13. Waves in which the motion of the particles is perpendicular to the motion of the waves as a whole are called:
14. Define longitudinal waves and give an example of this type wave:
15. Surface waves occur at the boundary between two different mediums.  The particles in the surface wave move both perpendicularly and parallel to the direction that the waves travels.

 11.2

1. Draw a transverse wave and label all its parts:
2. Know the following chart concerning properties of waves:

3. Define amplitude (for both transverse and longitudinal):
4. Define wavelength and given symbol:
5. Define period and give symbol:
6. Define frequency, give symbol, and SI unit for frequency:
7. Give the frequency-period equation and a sample problem:
8. Give wave-speed equation and a sample problem:
9. Seismic waves caused by earthquakes follow 2 main types:  P waves (primary waves) travel faster, are longitudinal, and shake the ground from side to side.  S waves (secondary) move more slowly but carry more energy, are transverse that shake ground up and down.
10. Solve the practice problems 1 through 4 on page 370.   Show all formulas, variables filled in with data, and final answer, with units, circled.
11. Describe the differences in speed of a wave in different mediums and why kinetic energies are involved:
12.  Give an example of the Doppler effect:

 11.3

1.  Explain reflection of waves at free boundaries and fixed boundaries:

2.  Give an example of diffraction:

3.  Define interference:

4.  Recreate the Figure 11-20 drawing.  Label all parts.

5.  Describe why soap bubbles create such a variety of colors:

6.  Standing waves:  reflected waves with the same amplitude, frequency, and speed as the original  wave form standing waves.  These waves do not move through the medium but cause the medium to vibrate in a loop or series of loops.  Define nodes and antinodes:

7.  Draw or explain the possible specific wavelengths that can form in standing waves.

Answer the following questions on pages 381 – 382:

1-10

13

16

19

21

22

23

Chapter 12

12.1 

1. Review the Table 12-1 on page 391
2. Give the speed of sound in air at room temperature:
3. Why do sounds travel faster through liquids or solids than gases?
4. Explain the difference between loudness and intensity of sound.
5. Speed of sound in gases:  The speed of sound in a gas depends on the velocity of the molecules.  Temperature is a measure of the average kinetic energy of the molecules so the average K.E. of the molecules of any matter at the same temperature is the same.  Molecules of air at 0° C have the same K.E. as molecules of hydrogen or helium.  However, molecules in air have an average mass of about 29 u (atomic mass units) whereas hydrogen molecules have a mass of 2 u and helium 4 u.  The kinetic energy depends on the mass and velocity (K.E. = ½ mass x velocity²).  Therefore, in order to have the same K.E., molecules of hydrogen and helium must be moving much faster than molecules of air.
6. Remember that amplitude of sound waves is determined by the degree of compression (and the degree of rarefaction) compared to the normal pressure of the medium.
7. Relative intensity is measured in:
8. The quietest sound a human can hear is ______dB.  The threshold of pain is about __________dB.   Extensive exposure to sound about _______dB can cause permanent deafness.
9. Pitch is related to the _____________ of sound waves.
10. Define infrasound and ultrasound.
11. Explain how a musical instrument develops its characteristic sound quality (related to harmonics).
12. Describe how the human ear processes sound waves.
13. Define sonar, resonance, sonograms
14. Using common objects or musical instruments demonstrate the following

a) two sounds of different intensities but the same frequency

b) two sound of different frequencies but about the same intensity

c) two sounds of different pitches but about the same amplitude

d) two sounds of different amplitudes but the same pitch

e) two sounds of different wavelengths but the same amplitude

12.2

1. Describe photons of light (in detail):
2. The speed of light in a medium is less than that in empty space.  The photons encounter the many atoms that make up the medium.  The atom’s electrons may absorb the light and emit it again which takes a very small amount of time.  When the light is traveling through the empty space between atoms is travels at c.  The speed of light in the medium is really an average that takes into account the absorption and emission of the light as it encounters the atoms.  Note the Table 12-2 on page 401 showing the more dense the medium, the slower the speed of light passing through it.
3. The intensity or rate at which light or any other form of energy flows through a given area of space follows the inverse square law.  Here, as the distance from a light source doubles, illumination decreases to ¼ its original value.

4. Give the values of light in nanometers (nm) that human eyes can detect.  Radiation in others parts of the electromagnetic spectrum is qualitatively not different than visible light.  Our eyes are sensitive to the frequencies in the visible spectrum.
5. Which end of the electromagnetic spectrum has higher frequencies?  Which end of the spectrum has longer wavelengths?  Which end of the spectrum has higher energy?
6. Remember that ultraviolet light can damage cells because of the high energy of the photons, which also gives it penetrating ability.  X-rays lie just beyond the UV part of the spectrum and have enough penetrating power to pass completely through the body.  X-rays are even more damaging to cells than UV of the same intensity.
7. Complete the Real World Applications problem on page 403.
8. Give real world examples of infrared light, microwave, and radio waves.

12.3

1. Define geometrical optics:
2. Specular reflection occurs when light hits a smooth, reflecting surface like a mirror.  What is the term for the type reflection off a rough surface?
3. Make a drawing showing the law of reflection off a mirrored surface.  Use a protractor to make the drawing correct.
4. Mirrors produce virtual images.  Explain this concept as it is compared to real images.  Remember that on concave mirrors can produce a real image.
5. Most household mirrors have a reflecting surface under a coating of glass.  Large telescopes and optical applications use first-surface mirrors where the reflecting surface, usually aluminum, is on the top surface.  Silver is only used to achieve an antique decorative look.  Aluminum is used instead.
6. When the brain receives signals from certain combinations of photoreceptor cells in the retina, it interprets them as color.  There are three kinds of cone cells; one each for red, green, and blue.   Lighting used in special cases might include lights over produce displays to make the produce look lush green and deep red, lighting at makeup counters and jewelry counters, and stage lighting.
7. Explain what happens when a green leaf is struck by white light, green light, red light, and no light.  How do we perceive the color of the leaf in each case?
8. Explain the additive property of primary colors of light.
9. Explain the subtractive primary colors of yellow, cyan, and magenta.
10. Explain what you have if you added all colors of paint pigment

12.4

1. Describe the important aspect of light called refraction:
2. Explain how fiber optics use total internal reflection:
3. Compare the effect on light beams of converging lens and diverging lens:
4. Trace a photon of light as it enters the eye.  Remember that the curved cornea is a lens.  It does about 70 percent of the focusing of the light rays to form an image.  The lens’ curvature is changed by muscles to adjust for the focus for nearby and distant objects.
5. Show how a prism can demonstrate dispersion of white light into the color spectrum.  You might remember that the speed of all colors of light is the same (in a vacuum).  It is only when light enters a material medium that the speeds of different colors become different.  Why would the violet light slow down more than red light?  This happens because, as you move toward the violet end of the spectrum, the light’s frequency (energy) becomes closer to the natural frequency of electron transitions between energy levels of the atom.  Thus, photons of violet light are more likely to be absorbed temporarily by atoms than are photons of lower frequency (less energy).  As a result, the higher frequency of light, the more likely it will be delayed.
6. The drawing of the water droplet causing a rainbow (Figure 12-37 on page 418) demonstrates both refraction and total internal reflection.  Explain.

Answer the following questions on pages 419 and 420:

1-21  (sorry – they are all good questions)