Should I stick it out in EE with weak-ish math?

[psparky]

That makes perfect sense! I think I may have been measuring current incorrectly. With the above statement, if you measure current from one end of the resistor to the other you wouldn't get the same reading would you?

Damn my lab professor with his laissez-faire attitude toward teaching.

@ the second topic
Now it makes sense why amperage kills and not voltage. Increased flow of electricity allows the stopping of the heart, at even low voltages. So it's current = amount, voltage = intensity?

P=IV good lord I hope everything stays so easy.

Correct...if you put the amp meter in parallel...you have effectively made a current divider...which doesn't tell you jack. The rest of your comments sound correct as well.

 

[psparky]

Here's another power equation...P=(I^2)*R. It's simply derived from plugging the V=IR into P=IV.

P=I*(I*R)

Also...(V^2)/R=P

Okay...KVL and KCL

Kirchoff's voltage law...Kirchoff's current law.

KVL...the sum of the voltages across the load or loads in a single loop equals the voltage source.

KCL...current in equals current out of a node.

 

[BuddhaBelly34]

This makes so much sense as to why I couldn't explain my results in my lab report. And I still got an A. I hate grades. They make no sense.

I speak with a lot of the Nepalese students in my classes and they tell me about their experience with school in Nepal. All I have to say is, holy crap. It's actually an accomplishment to pass high school there.

Okay, so with P=IV what does that tell us? Say a PSU for a PC. If I have a 650w PSU what does that mean? That it can send only a total of 650w (probably peak) across all of it's wires combined, or that it can send a total of 650w down each wire? Does what you say hold true for all PSUs?

Thanks so much for all of your help!

 

[psparky]

Lets talk about series and paralell. Let's use water for a teaching tool again.

When two resistors are in series...the water must flow thru one resistor...then thru the other resistor.

When two resistors are in parallel...the water must flow thru both resistors at the same time.

Capeche?

 

[BuddhaBelly34]

Got it.

 

[psparky]

This makes so much sense as to why I couldn't explain my results in my lab report. And I still got an A. I hate grades. They make no sense.

I speak with a lot of the Nepalese students in my classes and they tell me about their experience with school in Nepal. All I have to say is, holy crap. It's actually an accomplishment to pass high school there.

Okay, so with P=IV what does that tell us? Say a PSU for a PC. If I have a 650w PSU what does that mean? That it can send only a total of 650w (probably peak) across all of it's wires combined, or that it can send a total of 650w down each wire? Does what you say hold true for all PSUs?

Thanks so much for all of your help!

Not sure what a PSU is. But watts make more sense when calculated across a load...not thru wires or individual wires.

 

[psparky]

So let's finish up with the basics. First of all...when you have a voltage source with two resistors in series...the current thru the resistors is ALWAYS identical. If there is two amps thru the first resistor...there is two amps thru the second resistor even if their resistances are different. Once you find the current...You can then find the voltage across each resistor...and you will notice that KVL and KCL are satisfied...also that V=IR no matter how you slice it.

Series resistance...simply add the two resistors together to get there equivalent resistance.

Paralell resistance is slighter more complicated. (R1 X R2)/(R1 +R2)

 

[psparky]

Last two topics to complete your foundation for EE. Never forget this stuff!

Voltage division and current division.

When you have two resistors in series...they will often ask you what the voltage is across one of the resistors.

I'll say it two ways. When finding the voltage across a resistor in series with another resistor...take the resitor you are interested in and divide it by the sum of the two resistors...then multiply it by the voltage source.

Here's the same thing with term. If you are looking for the voltage across R1

Voltage source X ((R1/(R1+R2))= Voltage across R1

When all voltages are found...again you will find that V=IR...KCL and KVL are satisfied.

 

[psparky]

Current division is typically when you have a current source in parallel with two resistors in parralel. In other words...how much current goes thru each resistor. If both resistors are equal...current splits equally.

It's identical to the voltage division...except you take the resistor you are NOT intersted in...and divide by the sum of the two resistors.

If you want the current thru R1...Current source X ((R2/R1+R2))

It gets tricky...but if you take the currents you found in both branches and multiply by their resistors...the voltages will be equal! If the voltages are not equal...you did something wrong!

V=IR...KVL and KCL are satisfied.

Even in the dreaded AC...all these things are the same!

That's it for now. Master these concepts and you can pretty much get through 50% of your electrical engineering courses!
Practice, practice problems. Things will start clicking more and more!

 

[earlofwessex]

Very good explanations psparky!

Okay, so with P=IV what does that tell us? Say a PSU for a PC. If I have a 650w PSU what does that mean? That it can send only a total of 650w (probably peak) across all of it's wires combined, or that it can send a total of 650w down each wire? Does what you say hold true for all PSUs?

just to catch this, PSU is a power supply.
that 650W value should¹ be RMS, and it can supply a total of that when you add up all the loads². note that power is delivered over two wires, since it involves a voltage (which has to be between two places). almost universally in DC systems, the black wire is the return, called ground.
for eg: the potential difference will be between the Red and black wires, and the current will flow from the red wire through the load and back through the black wire (in the other direction, remember KCL?). these values give you your I and V for the eqn.

---
¹Marketing/sales people will use any figure they can to make something sound better
²Things are actually a little more complicated than this, but the concept is what's important at the moment.

 

[BuddhaBelly34]

Very good explanations psparky!


just to catch this, PSU is a power supply.
that 650W value should¹ be RMS, and it can supply a total of that when you add up all the loads². note that power is delivered over two wires, since it involves a voltage (which has to be between two places). almost universally in DC systems, the black wire is the return, called ground.
for eg: the potential difference will be between the Red and black wires, and the current will flow from the red wire through the load and back through the black wire (in the other direction, remember KCL?). these values give you your I and V for the eqn.

---
¹Marketing/sales people will use any figure they can to make something sound better
²Things are actually a little more complicated than this, but the concept is what's important at the moment.

Thanks for that. Yehp PSU = power supply unit. Also, note 1 is very laugh worthy. To the point that a certification process needs to be done on units to make sure they do what they claim.

And I'm still reading through everything sparky.

 

[psparky]

And I'm still reading through everything sparky.

Take your time. Considering I just gave you 50% of EE...Im guessing it's going to take a while to digest. You won't get the full understanding until you start working sample problems...and you start struggling and asking questions. That's where the learning takes place.

Oh ya...forgot one more basic. (There are several details for sure...but you have a good start) When you have batteries hooked up in series...the you simply add the voltages of the batteries. So two 12 volt batteries in series will deliver 24 volts. When you have two batteries in parallel...the voltage remains the same...just the batteries will last roughly twice as long.

One good definition of "in parallel"...is "the voltage across is the same." So whenever you have 2 or more loads (resistors) in parallel...the voltage will be the same across each load. If the voltage is not the same...they are not in parallel.

 

[BuddhaBelly34]

Take your time. Considering I just gave you 50% of EE...Im guessing it's going to take a while to digest. You won't get the full understanding until you start working sample problems...and you start struggling and asking questions. That's where the learning takes place.

Oh ya...forgot one more basic. (There are several details for sure...but you have a good start) When you have batteries hooked up in series...the you simply add the voltages of the batteries. So two 12 volt batteries in series will deliver 24 volts. When you have two batteries in parallel...the voltage remains the same...just the batteries will last roughly twice as long.

One good definition of "in parallel"...is "the voltage across is the same." So whenever you have 2 or more loads (resistors) in parallel...the voltage will be the same across each load. If the voltage is not the same...they are not in parallel.

I knew that about the batteries from doing some simple electronics stuff at home.

 

[SophusLies]

Considering I just gave you 50% of EE...Im guessing it's going to take a while to digest.

More like 5%. The EE students that I met in school were math and physics freaks. Some more math and some more physics but they certainly weren't just V = iR kids. They all knew a ridiculous amount of Fourier-stuff, complex analysis, vector calculus, PDE's (for Maxwell's equations), and probability.

I would not take EE lightly for math. I'm not trying to scare you but you're going to see some very serious math in an EE curriculum. When I saw the EE kids in my upper level math or physics classes they thoroughly impressed me with their talents. When I took set theory we had an EE kid that absolutely destroyed the class. When I asked him what he was doing to master the things in the class he told me he learned most of this stuff indirectly in his digital logic design classes, lol.

 

[BuddhaBelly34]

More like 5%. The EE students that I met in school were math and physics freaks. Some more math and some more physics but they certainly weren't just V = iR kids. They all knew a ridiculous amount of Fourier-stuff, complex analysis, vector calculus, PDE's (for Maxwell's equations), and probability.

I would not take EE lightly for math. I'm not trying to scare you but you're going to see some very serious math in an EE curriculum. When I saw the EE kids in my upper level math or physics classes they thoroughly impressed me with their talents. When I took set theory we had an EE kid that absolutely destroyed the class. When I asked him what he was doing to master the things in the class he told me he learned most of this stuff indirectly in his digital logic design classes, lol.

It doesn't scare me to learn upper level math, I just wanted to make sure that losing a negative sign now and again, or integrating one of the trig co-functions to be positive, etc... wouldn't be the death of me in the field.

 

[psparky]

More like 5%. The EE students that I met in school were math and physics freaks. Some more math and some more physics but they certainly weren't just V = iR kids. They all knew a ridiculous amount of Fourier-stuff, complex analysis, vector calculus, PDE's (for Maxwell's equations), and probability.

I respect your opinion...and it's great to know all the stuff you described...but for 99% of us electrical engineers...it's not really going to be used in our work career.

EE's and physics guys are definietly two compeltely different animals. I did complete the EE program...and recently took the FE and PE. The principals I described above are 50% of school...the FE...and the PE. Yes, I'm speaking from experience. AC isn't all that different to me because V=IR in either case! Haha!...sorry, but as long as I'm this forum...i will never get away from that!

And sure those concepts above can be learned fairly quickly...however...mastering them will take years. And yes, the circuits you get in all the tests are going to be way more complicated then I described...but if you master those basic rules you can go a long, long way. And obviously learning way beyond that is goal...but for this young man...he hasn't even started his first day...but I wanted to give him a clear approach to what is coming...because proffesors are generally clear as mud.

 

[SophusLies]

I respect your opinion...and it's great to know all the stuff you described...but for 99% of us electrical engineers...it's not really going to be used in our work career.

I see what you mean. I agree that in a job you won't use that much from school.

 

[BuddhaBelly34]

but I wanted to give him a clear approach to what is coming...because proffesors are generally clear as mud.

so very true it hurts

my lab professor has some sort of disdain for teaching. he pushed back a lab so that we can, essentially, google the concepts.

 

[sophiecentaur]

Voltage is Potential Difference - the difference between the Potential on one side and the potential on the other (= Across the gap). Nothing is 'going through' - until you give it a path. Then Current flows Through the load you connected.

If someone says "I had 240V going through me" then their language is more shocking than the experience they had!

 

[sweetpotato]

As a practicing EE, IMO psparky gave the OP 50% of EE *that you will use on the job*, but about 10% of the EE they will expect you to know at school.

 

[BuddhaBelly34]

My first professor told me that getting his undergrad in EE was harder than both of his graduate degrees in the field. Do you guys feel the same?

 

[sweetpotato]

My first professor told me that getting his undergrad in EE was harder than both of his graduate degrees in the field. Do you guys feel the same?

I just have an undergrad in EE so can't really help there.

However, you need to keep in mind there are many reasons why this professor found it so hard. Did he have inadequate high school preparation? Was it hard for him to develop good study habits? You really can't draw any conclusions from that one statement alone.

 

[BuddhaBelly34]

He said that he "studied" by literally copying down the book word for word. So I would say his method of studying is rote learning.

Maybe he's just crazy. Cool guy though.

 

[psparky]

He said that he "studied" by literally copying down the book word for word. So I would say his method of studying is rote learning.

Maybe he's just crazy. Cool guy though.

The "harder" your courses are, the better for you in the long run. You are only going to work as hard as your prof's push you.

After you get your job...your GPA doesn't mean jack squat.

However, what you actually learned will matter imensely in the real world.

 

[real10]

To the original poster,
I just took the GRE recently and ended up with 760 on the math section...so yeah don't lose hope if u didnt do as well in high school...people end up doing better later on down the road...(i did better at penn state compared to HS and same thing with gre compared to HS) so yeah...depending on your undergrad institutions strength (my guess top 25 eng schools)...a B at min (of course higher the better) can signal u have understanding of the subject matter...a mix of A & B is def not bad at all by any means in engineering esp electrical eng...
and u can always work in some other field once u have a eng background... (maybe add a bus or liberal art minor maybe even linguistics lol)

 

[BuddhaBelly34]

To the original poster,
I just took the GRE recently and ended up with 760 on the math section...so yeah don't lose hope if u didnt do as well in high school...people end up doing better later on down the road...(i did better at penn state compared to HS and same thing with gre compared to HS) so yeah...depending on your undergrad institutions strength (my guess top 25 eng schools)...a B at min (of course higher the better) can signal u have understanding of the subject matter...a mix of A & B is def not bad at all by any means in engineering esp electrical eng...
and u can always work in some other field once u have a eng background... (maybe add a bus or liberal art minor maybe even linguistics lol)

The uni I will attend is ranked like 50th or so. University of Texas at Dallas. Not bad considering it is only a satellite campus. Then again it was founded by the TI guys so there is a lot of expectations from the school I bet. The JuCo I am at now is nothing special, but I bet it's on par with most every state university (outside of the major ones).

I am certainly doing better now than in HS, and for these past few chapters I have done exceptionally well. I just would hate to have no future in the field but work my butt off for the degree.

 

[charlesjeon]

To be honest, shouldn't it be depended on what sub-areas of EE that the OP is pursuing?

If you're interested in circuit theory, math shouldn't be too bad in general, whereas in RF and Signal (Communications) math is used extensively.

I've taken courses in signals/communications and have done LOTS of Fourier stuff.

 

[sweetpotato]

To be honest, shouldn't it be depended on what sub-areas of EE that the OP is pursuing?

If you're interested in circuit theory, math shouldn't be too bad in general, whereas in RF and Signal (Communications) math is used extensively.

I've taken courses in signals/communications and have done LOTS of Fourier stuff.

I agree. It not only depends on the sub-field, but also on the type of career the OP is interested in. Some electrical engineers will not use anything beyond arithmetic and basic algebra, some will get PhD's in signal processing which is a very math-intensive field.

 

[charlesjeon]

I agree. It not only depends on the sub-field, but also on the type of career the OP is interested in. Some electrical engineers will not use anything beyond arithmetic and basic algebra, some will get PhD's in signal processing which is a very math-intensive field.

Coding Theory even requires abstract algebra!

 

[eemichael83]

I agree. It not only depends on the sub-field, but also on the type of career the OP is interested in. Some electrical engineers will not use anything beyond arithmetic and basic algebra, some will get PhD's in signal processing which is a very math-intensive field.

Aside from Algebra and Calculus, I was a bit surprised to learn just how much Statistics is involved in something like Computer Vision. It seems to be nearly all Statistics and Linear Algebra. BTW, OP, you shouldn't feel like you have to have everything that you'll ever need to know learned by the time you graduate. There will almost always be some sort of on the job training or if you're in more of an R&D type field, you'll be doing just that... Research (Learning) & Development. The biggest thing that the University's teach you is HOW to think and solve problems.

 

[real10]

Aside from Algebra and Calculus, I was a bit surprised to learn just how much Statistics is involved in something like Computer Vision. It seems to be nearly all Statistics and Linear Algebra. BTW, OP, you shouldn't feel like you have to have everything that you'll ever need to know learned by the time you graduate. There will almost always be some sort of on the job training or if you're in more of an R&D type field, you'll be doing just that... Research (Learning) & Development. The biggest thing that the University's teach you is HOW to think and solve problems.

I agree at undergrad level CV it was more linear algebra (transformations)
on the other hand in almost all of EE -> statistics/probability is inherent and inescapable due to the ever present noise (real world situations) and modeling anything (data or noise) often requires one to characterize and identify it as part of a certain distribution (gaussian/normal seems appropriate most of the time...though uniform,rayleigh and others also pop up)
for example all that u learn at the start in EE most likely would be without statistics/prob (without noise) later on noise/real world factors make stat/prob more imp and make the same stuff harder (real world)

The funny thing about Fourier (series/transforms) is that the whole concept was invented to explain heat conduction in a metal rod...
EE people "stole" it ha!

 

[sophiecentaur]

Most of you guys are young. There are likely to be many changes in your lives and your jobs in the next few decades. I think it is very risky to decide on a Maths-based career (EE is certainly one of those) whilst assuming that you will be able to pick and choose which bit of Maths you will be prepared to cope with on the way through.
The technical world has a habit of changing very quickly and this always involves some new Maths coming to the forefront.
If you have reservations in your attitude to Maths then do another (equally demanding and prestigious) job and avoid having to deal with it.
Anyone who hints that you will get away without X,Y or Z ("I don't do Calculus" etc.) could be leading you astray. Fact is that you may have to cope with X,Y and Z, if you want to carry on with your chosen EE career. This shouldn't matter as long as you make the adjustment at the time but don't rely on sneaking in under the Radar.

 

[psparky]

Hey guys...I notice several of you using the word "maths".

I was going to say this is not correct...but when I looked it up in the dictionary...it is a word that is "chiefly British".

Interesting...in USA we say "math" whether it is singular or plural.

Learn something new everday...

 

[sophiecentaur]

You chaps have a lot to learn about grammar and spelling! :rofl:

 

[BuddhaBelly34]

Well, if it seems to be more about which field I want to specialize in I'm pretty sure that's going to be electronics or power engineering. Hopefully power engineering.

Thanks for all the replies!