PHYSICS 262

This is the third semester of a general introduction to physics.
We will study Optics and the history and foundations of Modern Physics this semester.

Optics is the study of the interaction of light with matter, and is divided into three distinct parts:

Geometrical, or Ray, Optics, where the interactions are such that a reasonable model for light uses rays following trajectories, which are straight until they come to some intersection of the media through which they travel;

Physical Optics, where we need a "finer" model, which uses the theory of Electromagnetic Waves, from Maxwell's equations; and, lastly,

the theory of Photons, where we need the more sophisticated models that take their basis in the work of Einstein in 1905, when he introduced the notion that light has its energy quantized, sized according to the frequency of the light in question: E = hf .

Modern Physics actually begins with the work of Planck (1900) and Einstein (1905) on photons, a century ago.
We will consider two large sections of Modern Physics,

special relativity, which describes the "unexpected" behaviors of things that move very fast, and

quantum theory, which describes the "unexpected" behaviors of the smaller particles that make up the world:
     molecules, atoms, protons, neutrons, electrons, quarks, and gluons.

1. We will follow the weekly, online class Syllabus. Your input, in terms of questions and comments, and your work with problems and exams, will help determine our pace, so that it may be updated from time to time. I note that the Syllabus given this semester is in considerable more detail than the ones I have given for the previous two semesters. It is important to read the material before classtime. Therefore I will occasionally give brief "quizzes" over the material to be covered that day, as a reminder that you do need to read the material before class!

2. From time to time, I feel we need some textual material appended to what is found in the textbook. Therefore, as they are created, I will put links here to additional material (which is required for the course):
   • The movies of the electric field lines for an oscillating electric dipole---that we viewed in class---may be found on the web at this URL for the far field, and at this URL for the near field.

     Yet another very interesting Java applet showing waves generated by oscillating charges can be found at this link.

   • Additional notes on Polarization of Light, especially circular polarization.
   • Interesting Java applet: it shows the E and B fields for a light ray, as they propagate along, and allows them to go through polarizers and for you to change the angles, etc.
   • Another, perhaps even more interesting Java applet: this one shows the detailed behavior of the E-field of a propagating light ray as it passes through a crystalline (bi-refringent) material, again allowing you to change the angles between the initial polarization vector and the optic axis, for example.
     Note that both these 2 new applets were located by a student in our class, and sent to me. Thanks!
   • A useful summary of the Sign Conventions for geometric (ray) optics and curved surfaces.
   • A different way of outlining the basic facts of the changes that Special Relativity makes relative to the ways we view the world.
   • The summary on the use of SpaceTime diagrams is at this location: Spacetime Diagrams (due to Minkowski). They will help you to better visualize relativistic relationships.
     
   • Due to in-class discussions, I have located some recently-published measurements verifying the basic "extra" assumption underlying special relativity theory, namely that the speed of light in vacuum is exactly the same for all observers. I put the URL's here, with the names for the headlines of the articles (which also have more links within):
     • A New Limit on the Overall Validity of Special Relativity,
     • The Most Precise Test Yet of special Relativity, to 1.7 parts in 10¹⁵,
     • Lorentz Violations? Not Yet!.
   • I have put here the calculations and pictures that concern details of the Twin Problem as discussed in class on 24 March.

   • A new set of additional notes has just been put here. They present some detailed philosophical considerations about the difference between classical physics and the (new) quantum physics which we are beginning to study.
     In particular they try to discuss the fact that what we call `` elementary particles" sometimes act (approximately) like classical particles, sometimes act (approximately) like classical waves, and sometimes like neither one.
   • A new set of additional notes has just been put here. They concern Planck's Law for the spectral radiancy of Thermal Radiation, and are required reading for the course. The material will be covered in class during the week that begins 7 April.
   • Also, please read Chapters 1 and 2 of Volume III of The Feynman Lectures on Physics, by Richard Feynman. You may find copies either by going to the Reserve Book Section at CSEL, and asking to borrow the book, or you can access it online from CSEL's new electronic reserve service, at this link.
     The bound copies are on reserve under either my name or the name/number of the class, or both.
     In order to access them electronically you will need the password for our class for this electronic reserve service. You should have received this password via email; if not, please ask me, or a fellow student.

   • the Hydrogen Atom:
     • Yet some more additional notes, as a .pdf file, are here. They concern the old, but very intuitive Bohr Model for the energies, mean radii, etc., for the electron in a hydrogen atom.
          A student in our class has found a number of interesting websites that talk about the Bohr model with very simple language and applets. They all come from a program at the University of Colorado, called Physics 2000, an interactive journey through modern physics! Some URL's are at this link and also this one.

       More modern material in the text and below; however, this is very useful, and rather straightforward.

     •    Mathematical Forms of Wave Functions, and good pictures of Probability Densities.
       This material is now "found" and is available here!

   • There will also be three examinations, homework assignments due (almost) every class period, and a comprehensive final examination.
     You must take all three of the examinations. The final examination is comprehensive, BUT OPTIONAL! However, you may use your grade on the Final Examination to replace your lowest examination grade if you so desire.

     The three exam grades and the homework will then each count 25% of the total grade for the course. The examinations will be during class time; you may use the Formula Sheets that I hand out in advance, for the exams and/or a single page that you have written yourself. The Final Examination is scheduled for 10-12 AM, Friday, 16 May.

     The grades will be "curved" so that the class average becomes a grade approximately a (high) C+.

     IF you miss an exam, you will make that up by taking the final examination; therefore, there will be NO make up examinations.

     • Older exam questions on optics are available at this link.
       

       Review and Equation Summary for the first exam may be downloaded, in Acrobat (.pdf) format here.

     • Older exam questions on special relativity may be found at this link.
     • Older exam questions on quantum physics may be found at this link.

   • The problem session, P. 267-001, graded CR/NC, is optional, but is very useful for help with the problems; it meets Friday at 9 AM, in Room 114 of Regener Hall. In order to receive credit for it, you must enroll separately. However, attenders are welcome even if not registered for that class. Since many of the topics in this semester are ``exciting,'' we will spend some time in P. 267 trying to answer questions raised in class that would take us too far afield during the regular classtime.

   • I strongly recommend the laboratory for this class, P. 262L. The material this semester is far from intuitive, mostly because it deals with very, very small things and/or things moving very, very fast. These phenomena are well outside of our usual realm of experience. Therefore, acquiring some better acquaintance, within the laboratory classes, is quite useful!
     There are two sections, one on Wednesday afternoon, and one on Thursday morning.

   • Assigned Homework will be very important in your process of learning the material being discussed. Therefore, it will count 25% of your final course grade.
     The majority of the required homework will be done, and graded, on the web, through the national program called Webassign. In order to use WebAssign, you must receive a "ticket" from me, allowing you access to the system, along with a "username" and a "password."

     You may click on WebAssign for a direct link to their website; however, you should set up your own bookmarks to get there more quickly and reliably.
     Although you can probably figure out what to do without any further directions, you can go to my WebAssign page for some more detailed comments about how to proceed.

     There will also be problems to be done directly on paper, and turned in.
     Some of them will be of the nature of Bonus Problems, which may be used to help out one's other HW grades. I will create solutions for both sorts, that may be accessed from links on the assignment pages as they become available.

     Direct links are given here to go to the listing of homework assignments, divided into three sets:

     1. homework sets I-XV, preparing for Exam 1;
     2. homework sets XVI-XXV, preparing for Exam 2;
     3. homework sets XXVI - XXXIX, preparing for the Third Exam;
     Links to the solutions are provided on the homework assignment pages.

Each of you must have a computer account.
Please use the e-mail facility on the class home page to send me your address, or give it to me in class.

   If you are a qualified person with disabilities who might need appropriate academic adjustments, please communicate with me as soon as possible so that we may make appropriate arrangements to meet your needs in a timely manner. Frequently, we will need to coordinate accommodating activities with other offices on campus.

Once again, a special welcome to you all. I expect our working together at learning some physics to be a very rewarding time.

Below you will find various weblinks to things happening in physics and astronomy.

Links to Exciting Physics News

Updated regularly.

• The regular weekly set of newsreleases from the American Institute of Physics can be found here.
• A little bit of information about the frequencies used by microwave ovens can be found at this website.
• Artificially-created materials that have indices of refraction that are less than 1. See this URL, or this one.
• New tabletop-sized laser system makes positrons while you wait!
• Everything you ever wanted to know about Modern Particle Physics, with guided tours, etc.
• Interesting, elementary discussion about anti-matter,, put up by the Stanford Public Relations people, relative to their new discoveries of B mesons.
• Highest Power Laser ever yet built [as of 11 Nov., 1998]
• Online copies of the standard Table of the Nuclides:
  • A zoomable .pdf-version, from Lunds University in Sweden
  • an online, searchable version, from Lunds University in Sweden
  • a searchable one in a different format, from Brookhaven National Laboratories, Long Island, NY
• electronic structure of ground states of each of the elements, in a pdf-file
• latest values of the constants in physics
•    easily-read graphics showing the different kinds of elementary particles that exist in our world.
• An index for pictures of famous physicists is at this location.
  • One of their best sources is at the History of Physics page , run by the American Institute of Physics.

• Astronomy Picture of the day
  • Index to the complete list of their pictures.
• The Hubble Heritage Program,
  with galleries of photo's from Hubble---new ones monthly
  • A collage, and link-index, of Hubble's pictures of Saturn
• latest data on distant supernovae [this one exploded 11 billion years ago]
• Adaptive Optics Telescope homepage, and pictures linked from there.
• COBE satellite data on cosmic microwave background
• footstep on the moon
• Albert Einstein picture and many links to his thought

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