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Bullshit Level : Engineer (i2.lulzimg.com)

submitted ago by [deleted]

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[–]mononaut 57 points58 points ago

For what it's worth, here's the correct answer: a capacitor is defined as two conductors separated by an insulator. It is, essentially, an "open" (disconnected) circuit, so direct current can't pass through it. However, when a voltage is applied to one side, the charge built up in one of the plates will exert a force on the electrons in the opposite plate, and you get a very brief current through the rest of the circuit. If you alternate between positive and negative charge in the first plate, you can get an alternating current in the circuit connected to the second plate, but it's all the same "charge" just flowing back and forth.

[–]appletart 4 points5 points ago

Wow! I had to do an electrical fundamentals module as part of my degree, could do all the relevant maths but would be entirely incapable of explaining it as succinctly as you just have. Cheers!

Could we trouble you for your take on inductors?

[–]mononaut 4 points5 points ago

Haha, thanks. My understanding of electromagnetism is pretty lacking, so unfortunately I can only describe inductors in mathematical terms. I just know that the number of turns in the coil is directly proportional to the "inertia" that it gives the current. The electrons going around the coil exert a force on the magnetic flux around it, but the flux has momentum and exerts a force back on the electrons to slow them down initially. If you then change the source voltage, the momentum in the flux resists changes in current. So, an alternating current with high enough frequency won't ever get the flux moving at all, so the resistance, which is proportional to the speed of the flux, never drops low enough to carry a current.

If anythings still unclear, I can try elaborate on any of these points.

[–]Crabxcore69 2 points3 points ago

The magnetic flux lines in an inductor align to keep current steady. The core, whether it be air or iron, create a path for the flux lines. Iron is used to give a higher Q, which relates to efficiency. The flux lines travel through the iron core and are concentrated letting less flux lines be dissipated. Think of an inductor as a condom, but with the tip cut off and attached to a straw. As the air coming into the condom has a greater "current" the condom expands (flux lines expanding). As the current lowers the condom shrinks down and try's to keep the same current coming out of the straw. It takes 5 time constants to shrink down to a 0 state. The time constant has to do with the input frequency and Inductance of the inductor.

  • I know electronics, but not very good at explaining. Poor English skills+autism. But I hope you can sift through and find relevance.

[–]appletart 1 point2 points ago

Mere modesty on your part! - I see no relevant problem with your English and would add that your descriptions are rather talented!

[–]Crabxcore69 1 point2 points ago

Glad I could help:D

[–]mononaut 0 points1 point ago

I've always thought of magnetic flux as a kind of invisible sludge that flows in the direction of the flux lines... It's the only way I can understand it exerting force.

[–][deleted] 0 points1 point ago

The voltage induced in the inductor is opposite to the voltage applied and opposes the changing current. If the current is constant, no voltage is induced into the coil of the inductor. Once the current has reached maximum, the inductor no longer opposes circuit current and acts like a short.

[–]papaslew 3 points4 points ago

would a simple, DC has 0 frequency been an acceptable answer?

[–]mononaut 4 points5 points ago

If I were a teacher I wouldn't accept it, or at least only give partial credit. You're describing a characteristic of direct current, with nothing to say about the capacitor, so you're not fully answering the question. I'd be a hard ass of a teacher, I guess.

[–]papaslew 1 point2 points ago

im actually impressed by that response. you would be a great teacher!

[–]mononaut 1 point2 points ago

As a guy who just really likes studying electronics, I'm flattered :). Sorry your original question got downvoted. I wish questions like that were asked more often, as the worst thing that can happen is there will be a few more people that can answer it.

[–]papaslew 0 points1 point ago

As someone who studied Electrical and Computer engineering at a top university, I was just poking fun at the response. Not to say that I am caught up on my capacitor physics these days, but I do wish more teachers would have given explanations comparable to your response

[–]mononaut 2 points3 points ago

I see now :). I just get excited when presented with an opportunity to expand someone's scientific view. The most minimum correct answer would be, "capacitors are open circuits." it's technically correct (the best kind of correct) and answers the question completely.

Edit: by the way, what didn't your professors make clear that I did? This seems like really basic knowledge to me...

[–]papaslew 0 points1 point ago

I actually didnt mean any one topic in particular. I meant your explanation for why you would not accept that as an answer. I just remember a few exams I took that whether it be 0 credit or partial credit, did not provide an explanation.

[–]C_T_C_C 0 points1 point ago

It's really quite a simple concept if you take the mathematics out of it and simply diagram it mates. Not intending to be pompous or anything, but with basic experience from my AP physics B class from last year, I figured this out completely without referencing the top comment or the inter webs.

[–]Batmaners -1 points0 points ago

MFW reading this

[–]ALKINDA 5 points6 points ago

seems legit

[–]SakeBomberman 14 points15 points ago

but what if the capacitor has +5 resistence to AC enchant, then what?

[–][deleted] 5 points6 points ago

I'm sure the guy that did this would find a creative way to answer that too :P

[–]pyronova 4 points5 points ago

The fuck was this when I needed the answer for my Instrumental Analysis exam?!! WOULD HAVE SAVED MY ASS!!!

P.S. you're my hero.

[–]Sjokomelk 1 point2 points ago

I'm an electrical engineering student. I know how a capacitor react to DC hhigh frequencies and very high frequencies. I know how it resonates with a coil. I know when and why to use them in a circuit.

But I have no idea what so ever how they work.

[–]Klosu 1 point2 points ago

WoW. I'm studing it too atm, and we had it all explained before we even bagan to deal with circuits, on "theory of electromagnetism". What kind of university are you studing at?

[–]Sjokomelk 0 points1 point ago

Sure, I've studied it. I even got an A on the exam. That does in no way imply that I know it.

[–]Klosu 1 point2 points ago

Point taken.

[–][deleted] 6 points7 points ago

engineers don't really care how and why it works provided it just works ...

[–]gungywamp 5 points6 points ago

That's fucking terrifying.

[–]Angstrom88 1 point2 points ago

Bad engineers don't care.

[–]Captain_English 1 point2 points ago

...with a 10% tollerance.

[–]andrewtheernst 0 points1 point ago

i have to ask.. are you joking?

[–]ZyGlycan 1 point2 points ago

No, he isn't. When you're on a deadline and you're going to fired unless you finish up right now, you don't give a rat's ass for why it works.

[–]andrewtheernst 0 points1 point ago

Yes but you had 4 - 5 years of college to understand how things work. If it isn't in your respective field then I can see why it doesn't matter that much, but to say we don't care how stuff works, well.... that just sounds bad.

[–][deleted] 0 points1 point ago

true that

[–]bleedscarlet -2 points-1 points ago

Generally speaking, people who over generalize things are retarded.

[–][deleted] 3 points4 points ago

generally speaking, an engineer is nothing else than a problem solver.

[–]andrewtheernst 0 points1 point ago

yeah but, engineers understand how stuff works.. i mean... we DESIGN IT...

[–]ghettobacon 1 point2 points ago

depends on what type of engineering you do. As a mechanical engineer, I do not care how a capacitor truly works.

[–]andrewtheernst 0 points1 point ago

OK, I'll give you that. But you must have had at least had ONE electrical systems class. I get if you don't know what a butterworth filter is, but to not know how the basic components of a circuit work is a little odd. But I dunno, I'm still a young gun. I'm sure when I'm middle aged I'll forget how some things work.

[–]ghettobacon 0 points1 point ago

Just so you know I'm still a student. But Yes I did have a electrical engineering course, but learned more about capacitors in Physics. Also we VERY briefly discussed butterworth filters, but focused more on high/low pass filters. Is that a type of low/high pass filter? I dont even know lol Either way, fuck bode plots!

[–]andrewtheernst 0 points1 point ago

I hated electrical systems with a passion.

[–]bleedscarlet -1 points0 points ago*

The entirety of my comment was lost on you. I was simply remarking at how dull of a statement it is to sum all of any single type of person into one mindset, and I thought by employing the same methodologies as you I might reach you on a deeper level (read: sarcastically). All Jeans are denim pants that I wear, but I won't put you on because you're just not that kind of Jean, Jean. Do you catch my drift? as it turns out NOT all jeans are denim pants I can wear.

In any case, bring on the downvotes. You're all idiots. (if you didn't catch the irony in this phrase, you probably belong at a website like 9gag)

[–]Dev1l5Adv0cat3 0 points1 point ago

Too bad we don't have the capacity to learn everything.

[–][deleted] -1 points0 points ago

as somebody who frequently over generalizes I take great offense to this

[–]Phexx 1 point2 points ago

There seems like there are more people than me who don't know what to say. I find this intriguing. Also, what?

[–]DeathByFarts 6 points7 points ago

Thats actually a good way to explain it. And pretty much accurate.

[–]mooble 1 point2 points ago

:( wut.

[–]spaceboundmonkeys 0 points1 point ago

Nice one.

[–][deleted] 0 points1 point ago

I upvoted this because it made me feel like I was smart enough to understand.

[–]J0SHWAR 0 points1 point ago

That doesn't sound right but I don't know enough about electrical currents to dispute him.

[–]WhyN0tZ0idberg 0 points1 point ago

*It's

[–]misterfanwank 0 points1 point ago

This is a wonderful mnemonic.

[–]pjwork 0 points1 point ago

I nearly crapped myself with laughter, thank you!

[–]baltakatei 0 points1 point ago

Cmd+F searched for "flux capacitor". Was disappointed.

[–]Arduinna 0 points1 point ago

I'm regretting showing this to my engineer boyfriend...I just got an hour long lesson on electricity that I really didn't want...

.<

[–]vinnleet 0 points1 point ago

Woah, your name OP... It's close to what I put when mine is taken. Yay :D

[–]AngryTortoise 0 points1 point ago

Turns out one of my flaws is engineering cause it seems logical enough for me

[–]john_nyc 0 points1 point ago

I would have gone with the Because It's Science and we have to accept that as my answer

[–]dukishlygreat -2 points-1 points ago

Billshit LEvel : High School Physics... FTFY

[–][deleted] 2 points3 points ago

Naw m8 .. this is college. Freshman year, electrical engineering

[–][deleted] 0 points1 point ago

you did not get this first hand, I have seen this many times on the internet

[–][deleted] 0 points1 point ago

Course not .. when did I even claim to? I'm just familiar with the state syallbus and exam patterns, is all

[–]vrieevriee -2 points-1 points ago

Weird, learned this in 11th grade physics.

[–]internetsanta 0 points1 point ago

Freshman year in college is usually all stuff that you learned in high-school. Difference is that hopefully the second time around you actually remember some of it.

[–]perdidoentx 0 points1 point ago

Learned this in basic electricity & electronics school in the Navy.

[–][deleted] 0 points1 point ago

Sure ... we did too.

Where I'm from though, not much thought is put into revising degree syllabi, so we get taught this stuff all over again

[–]1wiseguy -1 points0 points ago

This is the coolest thing about being an EE. Nobody understands what you do, so you can just make up stuff.

An ME is the worst. Everybody owned a LEGO set at some point.

[–]codewench 5 points6 points ago

With engineering you can bullshit all you want, but reality doesn't really care. Either it works, or it doesn't.

(also, sometimes it catches on fire.)

[–]JonnyPooner 0 points1 point ago

I bet you'll find the kids who actually turn out as MechE had mechano...

[–]krowefosho 0 points1 point ago

I think owning LEGOs applies more to civil engineers.

[–]pumpkindog -1 points0 points ago

404'd!!!!!!

[–]HedonisticRush -1 points0 points ago

he used a normally open contact symbol for his drawing :/

[–]RNRSaturday -3 points-2 points ago

Seems legit. (Hey, I'm a liberal arts major!)

[–]fackyuo -5 points-4 points ago

I thought it was cos DC is too chicken because edison was a twit, and AC is all michael j fox on that shit cos tesla is the man. :D

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