/sci/ - Science & Math » Thread #11368939

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Hey, /sci/

Anonymous Sat 08 Feb 14:20:10 2020 No.11368939 View Reply Original Report

Quoted By: >>11368942 >>11368965 >>11368993 >>11368994 >>11369073 >>11369279

Tell me it's possible cram DC circuits in a day.
I've got my first EE fundamentals exam tomorrow and I've yet to start studying.
The problem they give are really fucking hard and complicated.
The book has like 200 pages of theory.
This is far above HS level shit.

Anonymous

Anonymous Sat 08 Feb 2020 14:21:46 No.11368942 Report

Quoted By:

>>11368939

Should have taken modafinil and studied everyday like a fucking chink, now you know better

Anonymous

Anonymous Sat 08 Feb 2020 14:38:07 No.11368965 Report

Quoted By:

>>11368939
Dude, just learn basic shit and use your brain in the exam. Don't waste your time on anything other than basic principles because all those 200 pages will be undergired by those basics.

Anonymous

Anonymous Sat 08 Feb 2020 14:56:19 No.11368993 Report

Quoted By: >>11369000 >>11369020 >>11369089 >>11369114 >>11369264

>>11368939
Well, ill assume that by dc circuits you mean everything from simple single source, single impedance circuits all the way to rlc circuits.

What you NEED to make sure you understand is as follows:

>Basic DC circuits:
-Ohms law $V = IZ$
-kirchhoffs voltage law $\sum_{n} V_n = 0$
-kirchhoffs current law $\sum_{n} I_n = 0$
-power $S = VI = I^2Z$
-independent and dependent sources

>Basic circuit analysis
-mesh equations and how to set up a mesh matrix
-node equations and how to set up a node matrix
-super meshs
-super nodes

>Transitory state analysis for circuits with energy storing devices (capacitors and inductors)
- voltage in an inductor $V_L = L \frac{di_L}{dt}$
- for t =0 and inductor is an open circuit and for t = ? its a short circuit
- current in a capacitor $I_c = C \frac{dV_c}{dt}$
- for t = 0 a capacitor is a short circuit and for t = ? its an open circuit
- how to setup and solve homogeneous and non homogeneous differential equations

>Circuit analysis in frequency domain
- The Laplace transform (most important tool for EEs) $\mathcal{L}\{x(t)\}(s) = \int_{0}^{\infty} e^{-st}x(t)dt$
- special functions (distributions) such as step function, dirac delta, etc.
- modeling capacitors and inductors as complex impedances, $Z_L = j \omega L$ and $Z_C = \frac{1}{j \omega C}$
>Simple fraction decomposition
>Inverse laplace transform computation

Pretty sure thats most of it, best of luck bro, any questions you may have feel free to ask.

Anonymous

Anonymous Sat 08 Feb 2020 14:58:01 No.11368994 Report

Quoted By: >>11369005 >>11369089

>>11368939
Yes. DC circuits isn't terribly hard or complex. Ohm's law can be mastered in like 10 minutes. Basic series, parallel, and series-parallel circuits maybe 20 minutes. Power is simple like Ohm's law, 10 minutes. Thevanin/Norton's and other network theorems in like an hour. Capacitors, inductors, time constants and stuff maybe a half hour or so.

Forget a day. You can master DC circuits in about 2 hours if you apply yourself and you're not retarded.

Anonymous

Anonymous Sat 08 Feb 2020 15:00:42 No.11369000 Report

Quoted By: >>11369008 >>11369089

>>11368993
In most colleges calculus isn't even a co-requisite for DC circuits so the latter half of your post doesn't really apply and it's just going to confuse OP.

Anonymous

Anonymous Sat 08 Feb 2020 15:02:35 No.11369005 Report

Quoted By:

>>11368994
Shit you mentioned a ton of shit I forgot about.
Yeah make sure you understand thevenin, norton and all what this anon said

Anonymous

Anonymous Sat 08 Feb 2020 15:04:48 No.11369008 Report

Quoted By: >>11369040

>>11369000
Shit dude, in my uni calc 2 and physics 2 were prereqs for circuit analysis 1

Anonymous

Anonymous Sat 08 Feb 2020 15:10:01 No.11369020 Report

Quoted By: >>11369031

>>11368993
Why is power S?

Anonymous

Anonymous Sat 08 Feb 2020 15:12:41 No.11369031 Report

Quoted By: >>11369041

>>11369020
Shit, I wrote S out of instict.
You can write P, in this case its the same thing as S.

Anonymous

Anonymous Sat 08 Feb 2020 15:16:15 No.11369040 Report

Quoted By: >>11369264

>>11369008
DC circuits is literally the introductory electronics course in typical universities. Usually people go into it taking calculus 1 the same semester. The course is typically algebra focused although sometimes they'll apply some calculus for capacitors/inductors, depends on the program. You won't see Laplace in that course, that'd come later in analog/digital signal processing courses by which time you've already taken DC and AC circuits plus Electronics courses all your calculus and you're probably in differential equations that semester. Also the concept of impedance isn't even introduced until AC circuits since it's a frequency dependent parameter and that's not relevant at DC.

Whatever university you went to appears to be the exception, not the rule.

Anonymous

Anonymous Sat 08 Feb 2020 15:16:35 No.11369041 Report

Quoted By: >>11369124

>>11369031
You use Z instead of R so I assume you're either engineering or stating it more generally to include AC when the time comes. I'm just wondering why S if there's any reason or just an underused letter for engineers.

Anonymous

Anonymous Sat 08 Feb 2020 15:28:47 No.11369073 Report

Quoted By:

>>11368939
>Cram
Math is about making up questions based on the concept then solving them on your own to the point you can reflexively do the concept without thinking.

Anonymous

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Anonymous Sat 08 Feb 2020 15:33:19 No.11369089 Report

Quoted By: >>11369137

>>11368993
By DC circuits I literally mean just DC circuit analysis mostly.
Basically, I need to learn how to apply theorems and algorithms of circuit analysis to efficiently solve shit like pic related.
Thanks in any case.

>>11369000
We do use calculus in electrostatics.
That shit's easy, you don't really need much practice for that if you know the theory.
These circuit problems on the other hand...

>>11368994
Aaarghh thanks anon, I'll do my best.

Anonymous

Anonymous Sat 08 Feb 2020 15:47:37 No.11369114 Report

Quoted By: >>11369132

>>11368993
Our first year circuits included op amps and AC analysis along with everything else you wrote

Anonymous

Anonymous Sat 08 Feb 2020 15:51:23 No.11369124 Report

Quoted By:

>>11369041
For power there's P, S, and Q. P is real power and th unit is watts (W). S is apparent power and the unit is volt-ampere (VA), and Q is reactive power and the unit is volt-ampere reactive (VAR). P is real power, it's what you get with DC and it's irrespective of phase angle. Q takes the phase angle into account and S is basically the root sum of the squares of P and Q.

S and Q only come into play in AC systems.

Anonymous

Anonymous Sat 08 Feb 2020 15:53:19 No.11369132 Report

Quoted By:

>>11369114
We're doing electromagnetism and AC analysis in the second semester, that's EE fundamentals part two.
Part one is electrostatics and DC analysis (this exam is mostly the latter, the former was for midterms).

Anonymous

Anonymous Sat 08 Feb 2020 15:54:21 No.11369137 Report

Quoted By: >>11369141

>>11369089
I am perhaps exaggerating those times a bit but it should still be possible to do it in a day. It's really not as bad as it looks. Network theorems and nodal analysis and stuff are really more tedium than anything.

Good luck.

Anonymous

Anonymous Sat 08 Feb 2020 15:55:02 No.11369141 Report

Quoted By:

>>11369137
Thanks.

Anonymous

Anonymous Sat 08 Feb 2020 16:40:07 No.11369264 Report

Quoted By:

>>11369040
In my uni you had to take circuit analysis 1 after calc 2 and physics 2 and you took everything I mentioned in here >>11368993
+ Opamps
In circuits 2 it was al ac stuff

Anonymous

Anonymous Sat 08 Feb 2020 16:51:33 No.11369279 Report

Quoted By:

>>11368939
network theorems are the hardest part, which are an extension of your knowledge of V=IR. the time constant inductor/capacitor garbage is just remembering some equations.

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