Question 1: What is the relationship between electric ...



Student Responses to Reading Quiz #12, due Wednesday February 25

Question 1: Describe the relationships (if any) between wavelength, wave number, frequency, angular frequency, wave speed, and amplitude.

1. Wave speed is indipendant of all the other varialbes. It depends on the properties of the medium. We then see that the product of the wavelength and the frequency equals the velocity. The wave number is just a constant but is equal to 2(pi) divided by the wavelength. The amplitude is the maximum displacement from equilibrium. The angular frequency is equal to: the product of the wave constant and the velocity, 2(pi) multiplied by the frequency, or 2(pi) divided by the frequency.

2. Wave speed is equal to the waves frequency times the wavelength. Angular Frequency is equal to the wave number times the wave speed. The vertical displacement of a wave is equal to the amplitude times the sine of the wave number times the horizontal displacement minus the angular frequency times the time.

3. 1. Waves can diffract 2.The speed of a wave is not dependent on the speed it's source is moving, particles would feel the effect of the source's speed 3. Waves can transfer energy and momentum without the transfer of matter.

4. The speed of a wave is defined as the the frequency multiplied by the wavelength. The wave number is inversely related to the wavelength and it equals 2*pi/wavelength. The angular frequency, which we know from rotations equals 2*pi*frequency is also equal to the wave constant multiplied by the wave speed. The amplitude does not depend on any of these and is simply realted to the energy in the system.

5. k:=2 pi/lambda w = 2 pi f v = f lambda = w/k

6. v = wave length / period = frequency * wave length y(x) = amplitude * sin(wave number * x) wave number * wave length = 2 pi angular frequency = wave number * velocity = 2 pi * frequency

7. waves experience diffraction and particles don't. Waves don't move as freely from one subsance to another as particles do. Waves can combine, and particles don't

8. The wave speed is the wavelength times the frequency. Angular frequency is the frequency time 2pi. The amplitude and wave number are part of an equation that give the displacement of the wave.

9. The wave speed is related to the frequency and the wavelength for it is the product of the two. The position of the wave depends on the amplitude (A) and the wave number (k) such that y(x)=A*sin(kx+phase constant). Also, the wave number is equal to 2 pi divided by the wavelength. The angular frequency is equal to the product of the wave speed and wave number as well as 2 pi times the frequency. Therefore the displacement can also be written as y(x,t)=A*sin(kx-wt), where w is the angular frequency.

10. The wave speed is equal to the frequency times the wavelength. The angular frequency is equal to 2(pi) times the frequency. The wave number is equal to 2(pi) divided by the wavelength. The amplitude is independent of all these quantities.

11. The wave length is represented by lambda, and is the distance travelled in a period T. The number of waves per meter is related to wavelength as 1/lambda. The "wave number" (k) is 2*pi/lambda. The frequency is the velocity/lambda, so it is also inversely proportional to wave length. Angular frequency is related to lambda (wavelength) by 2*pi*velocity/lambda. The wave speed is the velocity in the mentioned equations, and equals the frequency*wavelength. I don't think the amplitude is dependent on the stuff mentioned above so much, but is part of a big picture equation including the angular frequency and wave number. So basically, there's a lot of interrelations between wavelength, wave number, frequency, wave speed....

12. Wavelength is the velocity of the wave divided by frequency. The displacement of the wave is the amplitde times the sine of (the wave number times the distance from the origin plus a phase constant).

13. speed is equal to the wavelength over the period, or the wavelength times the frequency, (v=Lambda/T=Lambda*f). for harmonic waves, the displacement is equal to the amplitude times the sine of the wave number plus the phase constant, (y(x)=Asin(kx+delta)).

14. Wavelength and frequency are inversely related and are both directly porportional to the wave speed. Wave number per time is frequency and multiplied by the velocity gives you angular frequency which is also two-pi times the frequency.

15. Wave speed is equal to wave length times the frequency. Also, displacement is equal to the amplitude times the sine of the wave number times a veriable x plus a phase constant.

16. The product of wavelength and frequency is the speed of the wave. A higher frequency means a greater wave number. Amplitude and angular frequency are used in the harmonic wave function.

17. the wave speed is equall to the wavelength over the period, which equals the frenquency times the wavelength. the wave number, k, is equal to 2 pi over wavelength. angular frequency is equal to kv which is also equal to 2pi frequency.

Question 2: Waves and particles are similar in that both can transfer energy and momentum.

Describe three (3) differences between waves and particles.

1. 1)Waves can transport energy without moving matter. 2)Waves can experience diffraction after hitting a solid object whereas particles are stopped. 3)Many properties of waves follow simple harmonic motion.

2. Only waves diffract which describes the bending of waves through a barrier with a small aperture. Their speed is independent of the motion of the source. The speed of waves only depend on the medium. Interference patterns are created when waves meet.

3. Part of a wave can be reflected by the surface, which in one dimension would send part of the wave in the opposite direction. Tunneling can occur when a wave can pass into a nearby barrier even though it has reach total internal reflection (when its wave function drops exponentially and becomes negligible)

4. One property unique to waves is diffraction. Waves spread out or scatter after encountering a barrier while particles would pass through without any change or be stopped by the barrier. Also waves interact with each other in methods or interference that can be constructive or destructive. Finally, in nonhomogeneous mediums waves don't have to travel in straight lines and behave like particles.

5. Waves reflect, refract and diffract, while particles do not.

6. -waves' motion are independent of the motion of their source. -longitudinal waves can only travel through mediums, particles can travle in vacuums -particles have mass, waves (sound, EM, etc) do not

7. When a wave encounters a barrier at some angle, some of it is reflected back, and some moves through depending f the angle and n. In diffraction is when a wave passes through a small slit and thenit expands at a large angle.

8. Waves are massless whereas particles have some mass. Waves can be reflected and refracted at the same time. Waves can move out radially where single particles can only move in one direction.

9. 1. when waves are emitted uniformly in all directions, the energy at a distance r from the source is distributed uniformly on a spherical surface of radius r. 2. Potential energy of wave depends on its slope and potential energy of a particle depends on distance (either gravity or spring) 3. The energy in a harmonic wave is proportional to the square of the amplitude

10. Waves cannot exist in a vacuum (excluding electromagnetic waves) because they require a medium through which to propagate; particles can exist in a vacuum. Waves require a source of disturbance from which they radiate outward; particles do not. Because each point on a wavefront acts as a secondary source of wavelets (Huygens' principle), waves possess the ability to go around obstacles (diffraction); a beam of particles lacks this ability.

11. The kinetic energy, potential energy, total energy, and momentums are calculated differently for segments of waves than particles. Particles are more discrete, and have masses associated with them, while waves do not actually have mass. Waves can experience diffraction and interference. There can be superposition of waves--waves can be broken down into harmonic waves of different frequencies, while when particles come together they collide and bounce off of each other and stuff. Moving charged particles can create waves, but waves cannot create matter.

12. The mass in waves does not actually travel, even if the wave does. Also, the energy due to a wave is caused by the vibrating of the particle, not the translational motion. An EM wave can travel with zero mass through a vacumm and have both energy and momentum.

13. waves transfer momentum without transporting matter, they can pass through eachother, and they can bend and spread out

14. Particles require a medium to transfer energy where not all waves do. Wave velocity depends soley on the medium it's traveling through and not dependant at all on the velocity of the source.

15.

16. Waves do not require matter to be involved in their transmission at all, but particles are made of matter. Waves experience refraction when passing into different medium. Waves also diffract when encounter partial baarriers, but particles do not.

17. wave velocity is independant of its source. Also, waves diffract when they interact with an obstacle, matter. Also, waves interfere constructively and destructively with eachother.

Question 3: When a wave goes from one medium to another, its speed changes. What other things happen to a wave when it goes from one medium into another or it encounters a barrier? Describe at least two interesting effects.

1. If a wave is moving from a slower medium to a faster medium, it may experience total internal reflection of the angle of incidence is greater than the critical angle. This is because the angle of refraction is great than 90 degrees, so the wave is instead reflected. Diffraction occurs when a wave bends after it is obstructed by a barrier.

2. Waves can be reflected. This means that when they hit a boundary either part of or the entire wave will be sent back to the direction it came from. Waves refract. This means that when the wave enters a medium in which its wave speed is greater, it will bend away from the direction of the normal to the surface. The critical angle is the angle at which an incident waves will reflect back into the medium in came from

3. I believe I understand most of the conceptual issues, a general overview of the sections would help. Any mathematical issues will come about after the assigned problems are done

4. One thing that can happen when a wave encounters a barrier is that it experiences diffraction or spreads out. The interesting effects of diffraction depend on the size if the slit or even the number of slits creating multiple diffraction patterns. Also the wave could experience total internal reflection, if it is going from one medium with a high index of refraction to one with a low index. This means the angle of refraction is 90 degrees.

5. It reflects, refracts and diffracts When a wave is incident on a boundary surface that seperates two regions of differing wave speed, part of the wave is reflected and part is transmitted. Diffraction is the bending of a wave around an obstacle or aperture when the wavefront is limited.

6. One waves can turn into two, one going in the direction it was traveling, one going the reverse, neither the same size as the first. The wavelength and shape of the wave can change dramaticaly.

7.

8. When a wave changes mediums, some of it can be reflected or refracted. When a wave moves into a medium with a different wave speed, the wave is bent either toward or away from the normal. The wave may also be reflected off the medium with the same angle as it hit the barrier.

9. Some things that could happen are reflection, refraction, tunneling, and diffraction. Refraction occurs when the ray that is transmitted is bent toward or away from the normal due to the fact that the wave speed in the second medium is either less or greater than that in the incident medium. Diffraction occurs because when a wave encounters an obstacle, it tends to bend around it, and therefore when a wave encounters a barrier with a small aperture, the wave bends and spreads out as a spherical or circular wave.

10. When a wave comes to a boundary separating two regions of differing wave speed, part of the wave is reflected and part is transmitted. Depending upon the properties of the two media, the reflected wave may or may not be inverted; in either case, the transmitted wave is not inverted. When a wave enters a new medium, it is refracted toward or away from the normal depending upon the relative speed of the wave in the two media.

11. Waves can experience relection and refraction, as well as diffraction. When a wave enters a material, part of the wave is reflected and the rest is transmitted into the new material. Actually, when a wave surpasses a critical angle of incidence it is totally reflected. When waves encounter obstacles, they can bend around the obstacle.

12. When a wave travels through another medium, it refracts, or the transmitted ray bends so that it is traveling at a different angle. Wavefronts can also diffract when travelling through a barrier relatively small compared to its wavelength, meaning the wavefront will bend around the edges.

13. when a wave changes medium it may reflect, refract, or diffract. when a wave in watter hits a barrier with a hole, the wave will go through and spread out. if a ray hits a medium interface at an angle greater than the critical angle it will completely reflect.

14. If a wave is totally reflected it rebounds without passing through a surface or causing any disruption. Light waves also bend and change speeds when encountering a different media.

15. One interestic effect is that if it enters a new medium, part of it is reflected backwards. Also, if the wave goes from heavy to light medium, the reflected wave is not inverted, but if it goes from light to heavy, it will be inverted.

16. When a wave passes from one medium to another where the indices of refraction differ, the wave will refract according to Snell's Law, or possibly reflect off of the boundary. The wave will diffract if it encounters a barrier with a gap. If a wave is in a medium where it has total internal reflection, and a another medium of the same type is brought close to it, some of the wave will penetrate the barrier or "tunnel" to the second medium.

17. One part of the wave is reflcted and part of it is transmitted. When encountering an obstacle, the light defracts and makes repeating patterns on a screen.

Question 4: What are the conceptual and mathematical issues from the reading that you would like to discuss in class?'

1. I don't quite understand what tunneling is. I have heard of quantum tunneling but dont know if it related.

2. I don't understand the general wave equation. It might be easier to follow once we've done partial derivatives in Calculus.

3. none as of now

4. None

5. Wave equations

6. none

7.

8.

9. I was really confused by question 2 and wasn't sure what part of the reading answered it.

10. The wave equation

11. just bring it all together, i guess

12. None.

13.

14. nope

15.

16. none

17.

Question 5: What concerns or issues do you still have with material from previous classes?

1. If you are given a B field vector in an EM wave, how can you determine the direction of the E field, and the direction of the velocity of the wave? and vice versa for E and B

2.

3. A little confused about the different types of antennas and orientations

4. n/a

5. none

6.

7.

8. None

9. not sure

10. Are the problems on the sheet assigned on the date given or supposed to be done by that date?

11.

12. and nope

13.

14. none

15. The direction of propogation of EM waves

16.

17.

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