The absurdity of US college textbooks

[5v333]

Actually i got the book for the em course yesterday.
"An introduction to electrodynamics", D. griffiths.

 

[user 37518]

Actually i got the book for the em course yesterday.
"An introduction to electrodynamics", D. griffiths.

That is a good one! Probably my favorite to begin studying EM. Only problem is that it is 100% physics, meaning that there are no engineering applications, its all abstraction, but the book is great. He also has a book on Quantum Mechanics, also very good.

I bought my copy of Griffith's Intro to Electrodynamics from Amazon, it is the hardcover US edition and I remember I paid a lot for it, but I bought the Quantum Mechanics book in the soft-cover International Ed. (which is another way of saying "Indian and Pakistani edition") and I remember I paid very little for it. Exactly the same content as the US edition, although the end of chapter problems might vary from the US edition, publishers do this to keep US college kids from buying the Int'l edition. Publishers are some of the worst scoundrels.

If you are interested, look up the story about the guy who got sued by book publishers for selling International Edition textbooks in the US, he won the lawsuit and it is now legal to sell or buy them in the US, still the publishers will place a warning on the Int'l edition cover saying "Sale in the US is forbidden", notice the word forbidden and not illegal.... What ends up happening is that re-sellers will place a sticker on top of the warning, sometimes these stickers say something like "Original" or "New Edition" or something like that.

Here in Mexico, book publishers sell some of these textbooks translated to Spanish, but for the last decade, they have been employing some really sneaky tactics, for example: in some cases they will omit the introductory chapters, or the appendix and solutions to odd problems from the book, or something similar, instead, they will provide an URL to access the missing parts online, and they still have the audacity to refer to the missing content as "extra materials". This is of course only done to save a couple of bucks on paper and ink, so you end up with a mutilated version of the book. What ends up happening is that in a few years time the publisher will remove the content from their servers and you will get a big "404 error" when trying to look for it.

 

[5v333]

5v333, quantum mechanics isn't as scary in reality as it sounds. There is also usually a very generous curve in those types of classes.

user 37518, is there an advantage for you getting another formal degree? I just ask because for me I found it easier (and cheaper) to just take classes and learn about things that truly interest you and then skip some of the rigid requirements and formalities.

Hope you are right. So far it has been very intense.
I just have a feeling that stuff will become super abstract and with calculations very different from classical physics.
But i am always worried about a new course.

 

[user 37518]

Hope you are right. So far it has been very intense.
I just have a feeling that stuff will become super abstract and with calculations very different from classical physics.
But i am always worried about a new course.

To be honest, I think that EM is harder than Quantum Mechanics, it depends of course, I am referring to a college course. But the thing with EM is that you need to use a lot of vector calculus like divergence, rotational, and different coordinate systems, there is a lot of geometry involved and you have to get coordinates right. And, at least in my experience, Quantum Mechanics involves partial differential equations with boundary conditions and stuff like that. I don't know, you'll be the judge but EM for me seemed harder, there is a lot more "drawing" involved, if that makes any sense.... But also, I totally love EM because all electronics derive from it, once you start learning about EM you begin to understand how electricity really works, the whole "electrons flow like water in a tube pipe" stuff that they teach in circuit analysis is a complete lie, but it works at low frequencies, it certainly works for audio...

 

[5v333]

I am interseted in em for the same reason. The foundation of electronics.
Vector analysis can be heavy but it is linear. Isnt quantum physics based alot on statistics etc?
I had a course in stats and discrete mathematics before the summer. It wasnt that hard but i never got an intuition for it.

 

[user 37518]

I am interseted in em for the same reason. The foundation of electronics.
Vector analysis can be heavy but it is linear. Isnt quantum physics based alot on statistics etc?
I had a course in stats and discrete mathematics before the summer. It wasnt that hard but i never got an intuition for it.

Yes there is probability and statistics, quantum can involve some nasty partial diff equations and integrals. I remember my "welcome" to the course was to derive Planck's Black Body radiation equation, which involves integrating a nasty exponential, not very hard once you get it though.

 

[5v333]

And you were very pleased with your self when it was completed.

 

[user 37518]

And you were very pleased with your self when it was completed.

I was both pleased and relieved.

Planck's theory is really clever, he solved what they used to call the "UV catastrophe", very ingenious solution to a problem which didn't make sense at the time. It basically started Quantum Mechanics.

 

[user 37518]

And you were very pleased with your self when it was completed.

How are the EM theory classes going? Did you enjoy the Laplacians, divergences, Jacobians, rotationals, change of coordinates and all the other beautiful vector calculus operations?

 

[5v333]

In three weeks we have gone through electrostatix, magnetostatik, e fields and b fields in matter, D fields and H fields, polarisation and magnetisation, bound charges and bound current, linear materials...
This week starting with electrodynamix i think.

Its like running after a train.

Vektor calculus is not new for us but things like multipole expansion with legendre polynoms is...

 

[5v333]

How is math for grownups going?

 

[user 37518]

In three weeks we have gone through electrostatix, magnetostatik, e fields and b fields in matter, D fields and H fields, polarisation and magnetisation, bound charges and bound current, linear materials...
This week starting with electrodynamix i think.

Its like running after a train.

Vektor calculus is not new for us but things like multipole expansion with legendre polynoms is...

That's where the good stuff is!

Regarding math for grownups. I am doing ok, too many tests for my taste, during the semester it summed up to 5-6 tests per course; almost one every 15 days, 2 of them were 'quizzes', the rest were full-fledged exams. In fact I am having one today and another tomorrow (and I still have the finals coming up). I detest tests, having a clock ticking down while you have to solve math problems is not my favorite cup of tea. Even worse when you check your work and realize that you screwed up in step 2 of a 15 step problem.

Proofs are also not my forte, I like them, but I am an engineer, I didn't take courses on how to write proofs like mathematicians do, so I also have been reading books of those sorts to get up to par. Also, I have been reading books on math notation (some of the proof books cover that) because mathematicians use a lot of symbols I was oblivious to.

Overall, hopefully I think I will be able to make it.

 

[5v333]

Induktion and ohms law today. Felt much better.

I think you will do fine!

The only tricks i have for exams are to come as prepared as I can and make sure my feet are not cold.

Dont forget, true mathematicians say the words "If and only If" almost all the time.

 

[user 37518]

Induktion and ohms law today. Felt much better.

I think you will do fine!

The only tricks i have for exams are to come as prepared as I can and make sure my feet are not cold.

Dont forget, true mathematicians say the words "If and only If" almost all the time.

Ohhh yes, "if and only if", "for all x", "a necessary and sufficient condition", etc...

The part I really like about EM theory is when you get to see the wave equation and how you derive from the Maxwell (actually Heaviside) equations the equation for a wave. I don't know if in physics you get to see the transmission line equations, but that is also great

 

[5v333]

Ill pay a little bit extra attention If it appears.

In many courses i had, we are intersted in things like conservation and conservative fields/forces.
Stuff like (maybe i rember wrong) divJ = - d/dt(charge density),
Continuity equation,
heattransfer equation,
etc.

 

[user 37518]

Ill pay a little bit extra attention If it appears.

In many courses i had, we are intersted in things like conservation and conservative fields/forces.
Stuff like (maybe i rember wrong) divJ = - d/dt(charge density),
Continuity equation,
heattransfer equation,
etc.

You are going to use the continuity equation again in your EM course. Yes, I guess that physicists are more interested in what you are talking about. I took Applied EM courses during my bachelor's and master's. They are really interesting, I mean, physics is great and all, but I think I would get bored if everything were just "charged spheres" and a "wire loop". When you use this stuff in antennas or in RF circuts, it is that you really appreciate it, otherwise it's just an abstract intellectual exercise and a way to play around with calculus, vectors and geometry.

 

[5v333]

And there it was today...
The wave equation and the speed of light in vacuum. All derived from maxwell's equations.

 

[user 37518]

And there it was today...
The wave equation and the speed of light in vacuum. All derived from maxwell's equations.

Nice! a work of art isn't it?

 

[5v333]

yes.
like a magical formula.

 

[5v333]

Just finalized and passed the course in EM theory. It ended with a 5,5h oral exam.
I am glad it is over

Looking forward to quantum physics, complex math and transform theory next.

How is it going for Dflip? What courses are you doing now?