The three worst diagrams EE students are presented with

On Saturday, October 5, 2019 at 6:22:50 PM UTC-4, snipped-for-privacy@columbus.rr.com wr ote:

rrows coming out of a dot on the center of the page ( or 8 or 24 depending on the book). This is what an electric field looks like on a charged partic le. Of course the new student does not know what a field is . the correct diagram would be a black smudge across the entire page because that might give some clue to the student that the field is everywhere. The notion that the field is everywhere is not such a trivial concept and the diagram that shows 16 arrows somehow does not really drive that point home.

Field lines seem to be a useful visualization to me*. You have to understand that the field strength is given by the 'density' of the lines. Didn't Faraday 'invent' the field lines?

George H.

*it gets 'fun' with moving charges... I recall this picture from the Feynman lectures for an oscillating charge, but I couldn't find it online.

so the answer is all sin waves. OK the whole purpose of the fourier seri es is to teach that any repetitive signal can be broken into sine component s and cosine components. SIN and COS ---(anybody listening?). So the firs t problem they show the student is the case where the cos waves are miracul ously missing. Isn't the whole point to show that you need sin and cos comp onents to faithfully make a repetitive waveform and the first thing you do is hide the cos waves????- WTF

y experience , the perfect control loop is the slowest , most overdamped lo op that you can build that is responsive enough to get the job done.

16 arrows coming out of a dot on the center of the page ( or 8 or 24 depen ding on the book). This is what an electric field looks like on a charged p article. Of course the new student does not know what a field is . the co rrect diagram would be a black smudge across the entire page because that m ight give some clue to the student that the field is everywhere. The notion that the field is everywhere is not such a trivial concept and the diagram that shows 16 arrows somehow does not really drive that point home. .

ram

e page.

udge.

I am not sure that the arrows with the additional heat map would help. I th ink that it would be better to introduce the student to a scalar field firs t. Really drive home the notion of a scalar field, ie a value for every po int in space. After the scalar field concept is driven home (even though i t would likely have to be done as a temperature field because that is relat able....every point in a room has a distinct temperature)then you can work in the vector field. The charge diagram requires two epiphanies at one tim e.

On Saturday, October 5, 2019 at 6:22:50 PM UTC-4, snipped-for-privacy@columbus.rr.com wr ote:

rrows coming out of a dot on the center of the page ( or 8 or 24 depending on the book). This is what an electric field looks like on a charged partic le. Of course the new student does not know what a field is . the correct diagram would be a black smudge across the entire page because that might give some clue to the student that the field is everywhere. The notion that the field is everywhere is not such a trivial concept and the diagram that shows 16 arrows somehow does not really drive that point home.

The field does not come out of a point charge. It just is. The analogy with sun is flawed because the sun radiates energy, the point charge does not. All the coordinates and field components are spherical. Drawing a picture i n 2D is worthless.

so the answer is all sin waves. OK the whole purpose of the fourier seri es is to teach that any repetitive signal can be broken into sine component s and cosine components. SIN and COS ---(anybody listening?). So the firs t problem they show the student is the case where the cos waves are miracul ously missing. Isn't the whole point to show that you need sin and cos comp onents to faithfully make a repetitive waveform and the first thing you do is hide the cos waves????- WTF

Dunno how the cos waves are miraculously missing. You can show that the ser ies coefficients, derived through integration of the cos x function product over a period, are zero.

y experience , the perfect control loop is the slowest , most overdamped lo op that you can build that is responsive enough to get the job done.

A piece of crap response like that usually has trouble following simple inp uts. You're thinking of junk from 40 years ago, the slide rule days, when i t was big deal to play with second order systems.

On Monday, October 7, 2019 at 6:25:29 PM UTC-4, snipped-for-privacy@gmail.com wro te:

arrows coming out of a dot on the center of the page ( or 8 or 24 dependin g on the book). This is what an electric field looks like on a charged part icle. Of course the new student does not know what a field is . the corre ct diagram would be a black smudge across the entire page because that migh t give some clue to the student that the field is everywhere. The notion th at the field is everywhere is not such a trivial concept and the diagram th at shows 16 arrows somehow does not really drive that point home.

th sun is flawed because the sun radiates energy, the point charge does not . All the coordinates and field components are spherical. Drawing a picture in 2D is worthless.

-- so the answer is all sin waves. OK the whole purpose of the fourier se ries is to teach that any repetitive signal can be broken into sine compone nts and cosine components. SIN and COS ---(anybody listening?). So the fi rst problem they show the student is the case where the cos waves are mirac ulously missing. Isn't the whole point to show that you need sin and cos co mponents to faithfully make a repetitive waveform and the first thing you d o is hide the cos waves????- WTF

eries coefficients, derived through integration of the cos x function produ ct over a period, are zero.

The point is that the student needs to see a problem with the sin/cos terms in the answer together to see how they work a phase shift into things. Bu t before the student (to be clear when I say "student" I mean "me") ever se es the beauty of the sin/cos working together they get the square wave prob lem with all odd (sin) terms. In my case I had a good notion about how the se repeating waveforms were comprised of frequency content on various harmo nics, but I do not think the phase issue gets driven home correctly and tha t is the real point of it all.

In my case I remember the prof showing the square wave and gloating about h ow he knows how it all reduces to sines and even cooler it is only the odd harmonics. I know this is messed up because it was the basis of my whole w ebsite I created and I know how this point had escaped so many trained prac titioners.

To be fair, it is so much easier to drive these points home with MATLAB and other tools. Perhaps they do a better job today.

my experience , the perfect control loop is the slowest , most overdamped loop that you can build that is responsive enough to get the job done.

nputs. You're thinking of junk from 40 years ago, the slide rule days, when it was big deal to play with second order systems.

are 16 arrows coming out of a dot on the center of the page ( or 8 or 24 de pending on the book). This is what an electric field looks like on a charge d particle. Of course the new student does not know what a field is . the correct diagram would be a black smudge across the entire page because tha t might give some clue to the student that the field is everywhere. The not ion that the field is everywhere is not such a trivial concept and the diag ram that shows 16 arrows somehow does not really drive that point home.

ection

y plot

etry --- so the answer is all sin waves. OK the whole purpose of the four ier series is to teach that any repetitive signal can be broken into sine c omponents and cosine components. SIN and COS ---(anybody listening?). So the first problem they show the student is the case where the cos waves are miraculously missing. Isn't the whole point to show that you need sin and cos components to faithfully make a repetitive waveform and the first thing you do is hide the cos waves????- WTF

p. In my experience , the perfect control loop is the slowest , most overd amped loop that you can build that is responsive enough to get the job done .

an arrow on every point on the page you get a black smudge across the page. A black smudge would be just as instructive as the 16 arrows from a charg ed point.

ength, which is a distinction you can capture with arrows.

while capturing the magnitude and direction features is a bit tricky.

e way of that.

Maybe you can get a better handle on this by consulting with that sorry ass weakling f*ck nobody pedophile buddy of yours.

On Saturday, October 5, 2019 at 6:22:50 PM UTC-4, snipped-for-privacy@columbus.rr.com wr ote:

rrows coming out of a dot on the center of the page ( or 8 or 24 depending on the book). This is what an electric field looks like on a charged partic le. Of course the new student does not know what a field is . the correct diagram would be a black smudge across the entire page because that might give some clue to the student that the field is everywhere. The notion that the field is everywhere is not such a trivial concept and the diagram that shows 16 arrows somehow does not really drive that point home.

so the answer is all sin waves. OK the whole purpose of the fourier seri es is to teach that any repetitive signal can be broken into sine component s and cosine components. SIN and COS ---(anybody listening?). So the firs t problem they show the student is the case where the cos waves are miracul ously missing. Isn't the whole point to show that you need sin and cos comp onents to faithfully make a repetitive waveform and the first thing you do is hide the cos waves????- WTF

y experience , the perfect control loop is the slowest , most overdamped lo op that you can build that is responsive enough to get the job done.

Lol, somebody must have pee'ed in your cornflakes...

1. don't know what a field it......all the instructor needs to do is a 1-3 sentence explanation of a field and a qualifier that what is shown in the b ook is a descritized version of a vector field. Basics college physics mat hematically define a field. The newer after 2000 version of Sears & Zemans ky or Serway & Jewett college physics books have nice isometric figures in color to show the field. If your brain can't process static drawings, there are LOTS of animations on line. Actually, a 'smudge' is totally wrong...how does a 'smudge' have magnititud e and direction?

3."Perfect" control loop is an incorrect statement. It all depends on the control performance requirements. Quite frankly, if the system requirement s specify no overshoot, so be it. One can't fight physics.

In the late 1980s a physics teacher attacked this problem, and ended up creating EM field animations with no "flux lines," they instead look like metallic wood-grain. This was HM Belcher's "project TEAL" for Physics 8.02, their undergrad course. Really excellent, especially see his mpeg animations of EM waves from dipole antennas:

(Find most of these on youtube also)

Sample-pak:

e are 16 arrows coming out of a dot on the center of the page ( or 8 or 24 depending on the book). This is what an electric field looks like on a char ged particle. Of course the new student does not know what a field is . t he correct diagram would be a black smudge across the entire page because t hat might give some clue to the student that the field is everywhere. The n otion that the field is everywhere is not such a trivial concept and the di agram that shows 16 arrows somehow does not really drive that point home.

irection

ity plot

mmetry --- so the answer is all sin waves. OK the whole purpose of the fo urier series is to teach that any repetitive signal can be broken into sine components and cosine components. SIN and COS ---(anybody listening?). S o the first problem they show the student is the case where the cos waves a re miraculously missing. Isn't the whole point to show that you need sin an d cos components to faithfully make a repetitive waveform and the first thi ng you do is hide the cos waves????- WTF

oop. In my experience , the perfect control loop is the slowest , most ove rdamped loop that you can build that is responsive enough to get the job do ne.

s?

w an arrow on every point on the page you get a black smudge across the pag e. A black smudge would be just as instructive as the 16 arrows from a cha rged point.

length, which is a distinction you can capture with arrows.

ge while capturing the magnitude and direction features is a bit tricky.

the way of that.

ss weakling f*ck nobody pedophile buddy of yours.

Which one? The description doesn't fit anybody I can think of, but you may have insights that sane people don't have access to.

--
Bill Sloman, Sydney

arrows coming out of a dot on the center of the page ( or 8 or 24 dependin g on the book). This is what an electric field looks like on a charged part icle. Of course the new student does not know what a field is . the corre ct diagram would be a black smudge across the entire page because that migh t give some clue to the student that the field is everywhere. The notion th at the field is everywhere is not such a trivial concept and the diagram th at shows 16 arrows somehow does not really drive that point home.

-- so the answer is all sin waves. OK the whole purpose of the fourier se ries is to teach that any repetitive signal can be broken into sine compone nts and cosine components. SIN and COS ---(anybody listening?). So the fi rst problem they show the student is the case where the cos waves are mirac ulously missing. Isn't the whole point to show that you need sin and cos co mponents to faithfully make a repetitive waveform and the first thing you d o is hide the cos waves????- WTF

my experience , the perfect control loop is the slowest , most overdamped loop that you can build that is responsive enough to get the job done.

Maybe I was out that day in class. I thought critical damping was the leas t amount of damping that settled monotonically, i.e. without overshoot. Al lowing overshoot provides for the fastest settling if you can specify a mar gin the settling needs to be within. Is there a way to calculate this in c losed form? I supposed you can define an envelope for the ringing and work with that, but I'm not sure that will be the fastest. Does the adjustment impact the frequency of the ringing or just the extent?

--

  Rick C. 

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Electrons? Sorry, i work with anti-positrons...

That movement also occurs between the parallel arrows.