Note: in addition to the two discussion sections on Thursday, which are in a previous post, there will be a student led study group on Thursday nights:
Thursday Study Nights:
Students interested in discussing the intellectual concepts introduced
in Physics 6C along with finishing a few last-minute homework problems
should attend this study group on Thursdays 7:00 p.m. This week it will be in the second floor lobby area of the ISB. Maybe in the future we will be able to get a room in Thiman or something.
Please come prepared by having already reviewed or completed most, if
not all, of the homework. Everyone is welcome to join these
collaborative discussions to not only reinforce, but clarify the
topics discussed in class and meet cool people.
Thursday, September 30, 2010
Wednesday, September 29, 2010
Student lead study group: Thursday 7 PM
There will be a student lead study group meeting on Thursday at 7 PM. See above for details.
Monday, September 27, 2010
Today's class, Monday
In today's class we will cover electric forces and electric fields. We will start with looking at the force between two charges, and then add a third charge on the x-axis and off the x-axis (two different cases). In that way we will do some vector addition of forces.
Forces are pretty concrete and tangible. A more abstract way of constructing a theory of electromagnetic interactions involves electric fields. In the second part of today's class we will look at the electric field due to one and two charges.
Forces are pretty concrete and tangible. A more abstract way of constructing a theory of electromagnetic interactions involves electric fields. In the second part of today's class we will look at the electric field due to one and two charges.
Sunday, September 26, 2010
Weekly discussion sections and office hours. Also e-mail.
You can get help with your homework, or other issues, at any or all of these weekly discussion sections. Please notice that there are three different rooms involved.
Wednesday; 5:00 -6:30 PM, ISB 235, (Trevor
Thursday; 1:30 -3:00 PM, ISB 165, (Eddy or Omar
Thursday; 6:00 -7:30 PM, ISB 356, (Gregory
My office hours are on Wednesday at 1:30-3:15 PM.
My office is ISB 243.
My email is: zacksc@gmail.com
Wednesday; 5:00 -6:30 PM, ISB 235, (Trevor
Thursday; 1:30 -3:00 PM, ISB 165, (Eddy or Omar
Thursday; 6:00 -7:30 PM, ISB 356, (Gregory
My office hours are on Wednesday at 1:30-3:15 PM.
My office is ISB 243.
My email is: zacksc@gmail.com
Friday, September 24, 2010
What this class is all about.
This class focuses on the study of electricity and magnetism. These two subjects were thought to be completely distinct (unrelated) is until around the 19th century. Electricity seemed very sharp, violent and dangerous (sparks, electric shock, lightning); while magnetism seemed very soft and subtle (mysterious pushing and pulling, compass needles, navigation). While the subject of their relationship was hotly debated, the consensus was that they were not related.
Our perspective now is that they are not only related, but inseparable. It is through relativity theory and a group of differential equations associated with Maxwell and Faraday that this relationship can be most profoundly understood. In this class, since those equations are a bit beyond the scope of what we can encompass, the relationship between electricity and magnetism will be, to some degree, an article of faith*.
In the first half of the quarter we will cover electrical phenomena. This includes the study of charged particles, electric fields, the forces and interactions between charged objects, movement of charged objects (current flow), and electrical "circuits". We will begin with chapter 20 which covers electrical charges, forces and fields**; we will skip chapter 21 (Gauss's law). Then we will cover electrical potential (chapter 22), which is related to potential energy as you may have learned about it in the study of springs and gravity in physics 6a (or in other physics classes you may have taken).
Chapter 23 covers electrical energy as stored, for example, in capacitors; while chapter 24 covers electric currents and conduction via the movement of electrons in metals. This allows us to transition to electrical circuits (chapter 25), which is a bit more phenomenological than the previous four chapters. We will learn to analyze and understand current flow in circuits with resistors and capacitors using something called "Kirchhoff's Laws". This is the last chapter that treats electrical phenomena in isolation, i.e., without considering magnetism.
Our treatment of magnetism begins with chapter 26 which introduces magnetic forces and fields, as well as the relationship between magnetism and electricity. Chapter 27 deals with a phenomenon known as electromagnetic induction. This allows us to understand a third circuit-related device: the inductor. The interesting oscillatory behavior of circuits with resistors, capacitors and inductors is explored in chapter 28. This is related to the nature of light waves moving through space, through which energy is transported in the form of oscillating electric and magnetic fields. This is the subject of chapter 29. Electromagnetic waves are important and intriguing. They are less tangible than water waves or waves on a string, yet they contain energy. Unlike sounds waves which involve an oscillation in the density of air, there is no medium through which they propagate. And yet they exist. A brief discussion, with an analogy to water waves, follows here.
While the theory of ocean wave generation and propagation is complex and nontrivial, it is nevertheless possible to visualize some essential aspects of it. One can imagine wind, from storms, producing activity at the surface of the sea. That activity, following sustained winds, can evolve into waves which can travel large distances over the surface of the ocean. Waves thus generated can travel, for example, from the Southern Pacific (southeast of New Zealand) to California.
In a roughly analogous manner, movement of charged particles (particularly electrons) can generate oscillating electric fields. These oscillating electric fields, in concert with oscillating magnetic fields which are also generated by the charged particle motion, can propagate over very large distances. These are are known as electromagnetic waves. Other names include: light, radio waves, infrared radiation, ultraviolet radiation, x-rays, etc; all of which are also sometimes described in terms of photons. The study of electromagnetism culminates in the investigation and appreciation of electromagnetic waves.
----------
* That may be a bit of an overstatement. Even without any equations, one can observe that electrical currents create magnetic fields. (Specifically, for example, they influence compass needles.) One can also observe that changing magnetic fields (magnetic fields that change with time) can induce electric currents. These phenomenological relationships, based on observation, establish a relationship between electricity and magnetism independent from that encompassed by mathematical equations.
** The concept of a field is a subtle and important one which pervades physics.
Our perspective now is that they are not only related, but inseparable. It is through relativity theory and a group of differential equations associated with Maxwell and Faraday that this relationship can be most profoundly understood. In this class, since those equations are a bit beyond the scope of what we can encompass, the relationship between electricity and magnetism will be, to some degree, an article of faith*.
In the first half of the quarter we will cover electrical phenomena. This includes the study of charged particles, electric fields, the forces and interactions between charged objects, movement of charged objects (current flow), and electrical "circuits". We will begin with chapter 20 which covers electrical charges, forces and fields**; we will skip chapter 21 (Gauss's law). Then we will cover electrical potential (chapter 22), which is related to potential energy as you may have learned about it in the study of springs and gravity in physics 6a (or in other physics classes you may have taken).
Chapter 23 covers electrical energy as stored, for example, in capacitors; while chapter 24 covers electric currents and conduction via the movement of electrons in metals. This allows us to transition to electrical circuits (chapter 25), which is a bit more phenomenological than the previous four chapters. We will learn to analyze and understand current flow in circuits with resistors and capacitors using something called "Kirchhoff's Laws". This is the last chapter that treats electrical phenomena in isolation, i.e., without considering magnetism.
Our treatment of magnetism begins with chapter 26 which introduces magnetic forces and fields, as well as the relationship between magnetism and electricity. Chapter 27 deals with a phenomenon known as electromagnetic induction. This allows us to understand a third circuit-related device: the inductor. The interesting oscillatory behavior of circuits with resistors, capacitors and inductors is explored in chapter 28. This is related to the nature of light waves moving through space, through which energy is transported in the form of oscillating electric and magnetic fields. This is the subject of chapter 29. Electromagnetic waves are important and intriguing. They are less tangible than water waves or waves on a string, yet they contain energy. Unlike sounds waves which involve an oscillation in the density of air, there is no medium through which they propagate. And yet they exist. A brief discussion, with an analogy to water waves, follows here.
While the theory of ocean wave generation and propagation is complex and nontrivial, it is nevertheless possible to visualize some essential aspects of it. One can imagine wind, from storms, producing activity at the surface of the sea. That activity, following sustained winds, can evolve into waves which can travel large distances over the surface of the ocean. Waves thus generated can travel, for example, from the Southern Pacific (southeast of New Zealand) to California.
In a roughly analogous manner, movement of charged particles (particularly electrons) can generate oscillating electric fields. These oscillating electric fields, in concert with oscillating magnetic fields which are also generated by the charged particle motion, can propagate over very large distances. These are are known as electromagnetic waves. Other names include: light, radio waves, infrared radiation, ultraviolet radiation, x-rays, etc; all of which are also sometimes described in terms of photons. The study of electromagnetism culminates in the investigation and appreciation of electromagnetic waves.
----------
* That may be a bit of an overstatement. Even without any equations, one can observe that electrical currents create magnetic fields. (Specifically, for example, they influence compass needles.) One can also observe that changing magnetic fields (magnetic fields that change with time) can induce electric currents. These phenomenological relationships, based on observation, establish a relationship between electricity and magnetism independent from that encompassed by mathematical equations.
** The concept of a field is a subtle and important one which pervades physics.
Thursday, September 23, 2010
Please post questions or comments regarding HW #1, or related material, here.
Homework 1 is due next Thursday (Sept 30). It includes 3 tutorials and a number of problems from Chapter 20. As you have probably done in previous physics 6 series classes, you enter your results online at the mastering physics site. (See the post: "Getting started..." for the link and other related info that will help you "get started".)
This assignment deals with the electric fields and forces associated with charge particles. A lot of the problems involve detailed numerical calculation involving things like k (in N-m^2/C^2) and q in coulombs. From personal experience I know that that can be pretty annoying and not fun. The answers rarely turn out right, and when you enter them it just says you are wrong with no explanation. At least you get 6 chances (the most they allow) and only a 1% penalty for incorrect entries. Some are more conceptual. My favorite so far is 48 (the answer is an integer).
The basic idea of the assignment is to get some familiarity and understanding of electric fields and forces, and their relationship to electric charge. I would suggest working the problems on paper, like you would on a test, before you try to enter your results online. One tip: remember to convert centimeters to meters, etc.. Unfortunately there are a lot of not small exponents, especially since we often start with charges of 1.6 * 10^-19 Coulombs (and then sometimes square that). Feel free to post comments and questions here, and remember that the primary goal of HW is to help you learn and to help you prepare for tests. Critiques of particular problems, their appropriateness, efficacy, etc., as well as questions and comments are most welcome here.
-Zack
This assignment deals with the electric fields and forces associated with charge particles. A lot of the problems involve detailed numerical calculation involving things like k (in N-m^2/C^2) and q in coulombs. From personal experience I know that that can be pretty annoying and not fun. The answers rarely turn out right, and when you enter them it just says you are wrong with no explanation. At least you get 6 chances (the most they allow) and only a 1% penalty for incorrect entries. Some are more conceptual. My favorite so far is 48 (the answer is an integer).
The basic idea of the assignment is to get some familiarity and understanding of electric fields and forces, and their relationship to electric charge. I would suggest working the problems on paper, like you would on a test, before you try to enter your results online. One tip: remember to convert centimeters to meters, etc.. Unfortunately there are a lot of not small exponents, especially since we often start with charges of 1.6 * 10^-19 Coulombs (and then sometimes square that). Feel free to post comments and questions here, and remember that the primary goal of HW is to help you learn and to help you prepare for tests. Critiques of particular problems, their appropriateness, efficacy, etc., as well as questions and comments are most welcome here.
-Zack
Physics 6c: Getting Started (2 websites...)
There are 2 different web sites associated with this course. They serve different purposes, which are complementary.
The first web site is this one, which you have found already. The purpose and function of this site is to communicate essential information about the class. That includes discussion of physics issues which come up in lecture, questions about the homework, information about what will be covered on the midterm and final, practive problems, etc.. Anything that might have traditionally been a hand-out, will appear here as a post. This is an interactive site, which facilitates discussion and follow-up; you can post your comments and questions here and get a response fairly quickly.
If you are stuck on a homework problem, it is okay, and encouraged, to ask about it at this blog. Then I, one of the TAs, or one of the other students in the class will answer your question. You are encouraged to become a "follower"; if you do that with a recognizable name (or send me an email letting me know the real name associated with your blog name), then you may get extra credit for your participation. In the past, I have found that interactive blog-type web pages (like this) can be useful for clarifying subject matter raised in lecture, for clarifying issues related to specific homework problems, and for preparing for the midterm and final. After lectures
The second web site is the Mastering Physics site at:
http://www.masteringphysics.com/
That is where you actually do your homework assignment. As in physics 6a and 6b, you will submit your homework problem results online at that site.
The first homework is due on September 30th. (You will find it at the mastering physics site.)
http://www.masteringphysics.com/
The midterm will be no sooner than October 22 and no later than Nov 5.
The final is on Monday, December 6th at 8:00 AM.
15% of your grade will come from your homework score (online).
35% of your grade will come from your midterm.
50% of your grade will come from your final.
The midterm and final will emphasize problem solving. The homework will help you develop your problem solving abilities, as applied to problems on electricity and magnetism. Although both are relevant, in my experience working problems tends to be a more effective than reading in preparing for tests. I would suggest solving the HW problems on paper, as you would for the midterm or final, and then entering your results online. That way you will tend to become more prepared for the tests that you will be taking later in the course.
The first web site is this one, which you have found already. The purpose and function of this site is to communicate essential information about the class. That includes discussion of physics issues which come up in lecture, questions about the homework, information about what will be covered on the midterm and final, practive problems, etc.. Anything that might have traditionally been a hand-out, will appear here as a post. This is an interactive site, which facilitates discussion and follow-up; you can post your comments and questions here and get a response fairly quickly.
If you are stuck on a homework problem, it is okay, and encouraged, to ask about it at this blog. Then I, one of the TAs, or one of the other students in the class will answer your question. You are encouraged to become a "follower"; if you do that with a recognizable name (or send me an email letting me know the real name associated with your blog name), then you may get extra credit for your participation. In the past, I have found that interactive blog-type web pages (like this) can be useful for clarifying subject matter raised in lecture, for clarifying issues related to specific homework problems, and for preparing for the midterm and final. After lectures
The second web site is the Mastering Physics site at:
http://www.masteringphysics.com/
That is where you actually do your homework assignment. As in physics 6a and 6b, you will submit your homework problem results online at that site.
The course ID is: physics6c
The first homework is due on September 30th. (You will find it at the mastering physics site.)
http://www.masteringphysics.com/
The midterm will be no sooner than October 22 and no later than Nov 5.
The final is on Monday, December 6th at 8:00 AM.
15% of your grade will come from your homework score (online).
35% of your grade will come from your midterm.
50% of your grade will come from your final.
The midterm and final will emphasize problem solving. The homework will help you develop your problem solving abilities, as applied to problems on electricity and magnetism. Although both are relevant, in my experience working problems tends to be a more effective than reading in preparing for tests. I would suggest solving the HW problems on paper, as you would for the midterm or final, and then entering your results online. That way you will tend to become more prepared for the tests that you will be taking later in the course.
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