Trying to prove a point - Page 1
Forum section: electronics / beginners

author: CoopedUp
author_rank: Regular Contributor
timestamp: June 06, 2019, 07:37:56 pm
content: So I'm not really a beginner but I figured this was the best place to put this. I had a packet for a class and this was a question on it. I want to prove to my teacher that he is wrong by having a poll I guess you could say of what answer you guys think it is and if I'm wrong I guess you can explain to me how I am wrong. I'm not going to say anything about what my answer is but just let me know.The abbreviations NO (normally open) and NC (normally closed) represent the electrical state ofswitch contacts whenA. power is appliedB. the switch is actuatedC. power is not appliedD. the switch is not actuated

author: ejeffrey
author_rank: Super Contributor
timestamp: June 06, 2019, 07:43:06 pm
content: D for a mechanical switch, potentially C for a relay as long as you are clear that is is power to the coil not to the switch contacts.

author: mikerj
author_rank: Super Contributor
timestamp: June 06, 2019, 07:46:03 pm
content: With the context provided in the question the answer has to be D.

author: dietert1
author_rank: Super Contributor
timestamp: June 06, 2019, 07:49:26 pm
content: I guess it should be D.If the switch gets actuated by an electro magnet (like in a relay), then C may be correct, too: The switch is not actuated as long as power is not applied to the coil.Regards, Dieter

author: bsudbrink
author_rank: Frequent Contributor
timestamp: June 06, 2019, 07:51:15 pm
content: A little vague, but D.

author: DimitriP
author_rank: Super Contributor
timestamp: June 06, 2019, 07:55:33 pm
content: Just to stirr things up....... A !

author: ataradov
author_rank: Super Contributor
timestamp: June 06, 2019, 07:58:27 pm
content: I don't get it. It says right in the name "normally". Normally open is always normally open, not matter what.But yes, it looks like they meant D.And that's exactly what I hate about those theoretical academia questions.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: June 06, 2019, 08:03:56 pm
content: What ejeffrey said.From vocational training i think i remember that position switches might be drawn in the initial condition of a machine - its mechanical state in which the machine is supposed to run in (e.g. housing/tamper evidence switch, NO, but drawn closed)."Normally" therefore refers to unactuated (as in holding it in hand), but a wiring diagram might show the normal mechanical state of the machine it is in.Depending on which symbols are to be used, it might be possible to include the type and direction of actuation in the diagram, giving away the clue if it is actuated in this state.

author: larrybl
author_rank: Regular Contributor
timestamp: June 06, 2019, 08:30:02 pm
content: Yes to Sparkly, I answered E-None of the above. From my diagramPedal Up = NOClutch OFF = NCNot Occupied = NCThe state of a switch in a diagram should be clarified.

author: StillTrying
author_rank: Super Contributor
timestamp: June 06, 2019, 08:52:09 pm
content: The answer has to be D.the switch is not actuatedC.power is not applied,is possibly a trap to check that you've read the question accurately, we all think "relay" when relay isn't mentioned anywhere, although it's always possible that the question writer doesn't know the difference.If I had put D and the supposed correct answer was C, I wouldn't let them get away with it!

author: DDunfield
author_rank: Regular Contributor
timestamp: June 06, 2019, 09:24:24 pm
content: The question says switch, as do two of the possible answers, so I would say 'D'.Worth noting that 'D' covers off a relay as well.One could argue that if you keep your computer on almost all the time, then it's switch is "normally" closed, however by convention the term "normally" applied to an electrical switch indicates it's position in a deactivated position.Light switch - deactivated is open, so it's "normally open".Reed sensor in a intrusion alarm, deactivated means loop not broken (closed), so it's "normally closed".DavePS: What did the teacher say was the correct answer?

author: neil t
author_rank: Regular Contributor
timestamp: June 06, 2019, 11:06:01 pm
content: If no diagram of the switch unit is supplied your teacher has asked a stupidly vague question, all the multiple answers are possible dependant on the type of unit.

author: JxR
author_rank: Unknown
timestamp: June 06, 2019, 11:13:45 pm
content: You didn't say what your answer was. How can we tell you if your wrong or right? Like everyone else said, the answer is D.This shows alot of pictures, while I only scanned it nothing immediately wrong stood out. Maybe it will help if your answer was not D.https://www.electronicshub.org/switches/

author: DDunfield
author_rank: Regular Contributor
timestamp: June 07, 2019, 01:59:46 am
content: Also worth mentioning that it's fairly unusual to see N.O and N.C. applied to switches which have two steady-states (toggle), since these can be used in either capacity. If it does appear it will be describing the switch function in the circuit, not the physical switch itself.The nomenclature is usually applied to switches which must be held in the active state, such as momentary push buttons, spring levers and relays.Dave

author: CoopedUp
author_rank: Regular Contributor
timestamp: June 07, 2019, 03:05:14 am
content: he says the only correct answer is c and refuses to accept that he is wrong, and let me tell you it's not the only question he made that had several correct answers... He's such a stubborn guy... I like him as a person just not as a teacher

author: CoopedUp
author_rank: Regular Contributor
timestamp: June 07, 2019, 03:16:06 am
content: And of course I picked D because it applyable to most switches. Another question asksA(n)______ converts light energy directly into electric energyA. phototransistorB. solar cellC. photoconductive cellD. LEDI wrote on the test that I'm sure all of them produce electricity when light is shown on them but I can personally vouch that b and d are correct. And his response was LEDs don't produce electricity when a light is on it... But they do and he's and electrical engineer... And he refuses to give me point because God forbid he's wrong

author: L_Euler
author_rank: Regular Contributor
timestamp: June 07, 2019, 03:18:35 am
content: He didn’t happen to explain what happens to the switch when power is applied did he?

author: CoopedUp
author_rank: Regular Contributor
timestamp: June 07, 2019, 03:20:01 am
content: His only explanation had something to do with a home switch in a cnc but it wasn't correct

author: Gregg
author_rank: Super Contributor
timestamp: June 07, 2019, 04:05:15 am
content: For a relay, C is a subset of D. If power applied means to the relay coil; the question does not state this. A rational person reading the question does not know what is meant by “power applied”; therefore choice D is far more rational and correct for more switching situations.For a manual switch, choice C doesn’t make any sense when considered as an answer to the stated question. However, D makes more sense than C but the question is very vague and flawed.The question should be:The abbreviation NO (normally open) represents the electrical state of:ORThe abbreviation NC (normally closed) represents the electrical state of:The teacher is trying to combine two questions into one; without a suitable answer.Those who can — doThose who can’t – teachThose who can’t even teach – can have a career in management or marketing

author: ejeffrey
author_rank: Super Contributor
timestamp: June 07, 2019, 04:23:15 am
content: Quote from: CoopedUp on June 07, 2019, 03:16:06 amOK, on that one you are just being a pain in the ass. The answer is clearly B, and saying anything else is stupid even if in some situations the other devices can do it. That is why most multiple choice exams state "circle the best answer" or similar at the top. The best answer to that question is B, and I would absolutely not give you a point for any other answer.

author: garethw
author_rank: Regular Contributor
timestamp: June 07, 2019, 05:48:51 am
content: D. Sent from my iPhone using Tapatalk

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 07, 2019, 08:26:19 am
content: Quote from: CoopedUp on June 07, 2019, 03:05:14 ami'm a teacher by proffesion for already 15 years. my answer is that, thats not a good question, its called ambiguous question. since in order to actuate a switch (relay) you need to apply power, hence not actuated = power not applied, answer either C or D should be correct (from my understanding and experience). the problem with teacher, esp young teachers, albeit they are good at teaching, not necessarily good at making questions. good questions need to be peer reviewed, if we get different answers from different teachers in the same subject, that means its a flag that the question is ambiguous. different students/readers have different experience, we need to rule that out so everybody with good knowledge from various discipline should end up with the same answer. if ambiguous questions already given to students in a test we teachers in the panel usually end up with 2 or more correct answers before marking. tell this to your teacher, or better tell this to the other teachers in the same subject so they can advice their peer. some teachers are usually too ego to get advice from their student. ymmv.

author: dietert1
author_rank: Super Contributor
timestamp: June 07, 2019, 08:52:35 am
content: No, a switch can be actuated by other means. For example end position/calibration switch in a machine, alarm system reed switch and power button of a notebook. Each one is a NO or NC switch.Regards, Dieter

author: DDunfield
author_rank: Regular Contributor
timestamp: June 07, 2019, 09:00:43 am
content: Quote from: CoopedUp on June 07, 2019, 03:05:14 amThe only way I could see this being even partially correct is because the original question says "electrical state".A normally-open button, not pressed has it's contacts open whether or not power is applied.A normally-closed button not pressed has it's contacts closed whether or not power is applied.It appears your teacher is looking at it in terms of current flow (electrical state?):N.O. button is an open circuit when power is applied.N.C. button is a closed circuit when power is applied.A "trick" question that has very little to do with actual knowledge.EDIT: Just re-read the original, C is "power is NOT applied". So I don't see any way for C to make sense. The above would argue (albeit weakly) for A "Power is applied".Dave

author: exe
author_rank: Unknown
timestamp: June 07, 2019, 09:02:08 am
content: I don't like such questions. Why can't they put it as "what is default state of a normally open (momentarily) switch"? Looks like they over-complicate things just to pan students. Why doing this? Give knowledge, not frustration.

author: brabus
author_rank: Frequent Contributor
timestamp: June 07, 2019, 09:11:08 am
content: The correct answer is D.No relay is mentioned, so a "switch" can be any manually activated switch, or a relay as well. The question only says "electrical state of the switchcontacts".Your teacher is very likely aware that the question is badly formulated, and that D is the correct answer, but he must defend his role as an educator*. What would happen if he accepted your point, even if it's correct? He should revise all the tests and reformulate the scores, surely facing hundreds of students who want to keep their marks.It is a lot easier for him to just state his point, without giving you a clear explanation whatsoever.You, as a student and a growing man, are learning a lot more from this experience than just the definition of a bloody switch.*Otherwise, as often happens, he is just a poor chap that randomly snake his way into education, with no interest at all in sustaining a conflict of ideas with a student - we all know that kind of guy.What I would do:- Avoid conflict, of course.- Buy a NC push button, bring it to class, and ask your teacher, following the answer C, how the NO/NC status of the switch is anyhow influenced by the power applied (to what?).

author: DDunfield
author_rank: Regular Contributor
timestamp: June 07, 2019, 09:21:00 am
content: Quote from: dietert1 on June 07, 2019, 08:52:35 amThree examples of momentary switches which must be held in the activated state, either by a moving part of a machine, presence of a magnet in close proximity or by a notebook cover pressing on it's little "stub". These switches will resume their "normal" state when the source of activation is removed.The "normal" state has nothing to do with whether or not the switch is held active more or less than it is held inactive, it is the state the switch assumes when there is no activating force applied to it. which is why the terms don't really apply to switches which naturally have more than one steady state.When you spec. a toggle switch, you don't care about N.O. or N.C. because the switch can be used either way (unless it happens to have ON/OFF markings on it and you want them to match the logical function of your device). For a momentary switch the distinction becomes important as you must decide which states represents "activated" and "deactivated".Dave

author: DDunfield
author_rank: Regular Contributor
timestamp: June 07, 2019, 09:25:34 am
content: Quote from: brabus on June 07, 2019, 09:11:08 amYou should make it one with visible contacts, otherwise you can't observe it's state without applying powerDaveYeah - I know the pic is a N.O. button, but you get the idea.

author: DimitriP
author_rank: Super Contributor
timestamp: June 07, 2019, 09:45:35 am
content: Does a device have an electrical state when power is not applied?Doesn't an "electrical state" imply existence of ....electricity?Or to put in in other words, what's the weight of an elephant with no gravity "applied"?

author: DDunfield
author_rank: Regular Contributor
timestamp: June 07, 2019, 10:15:59 am
content: Quote from: DimitriP on June 07, 2019, 09:45:35 amYep - I interchanged A and C when I referred back to the questions, probably because that was the only way the teachers answer could make any sense. "Power not applied" makes no sense at all, especially if you try to justify it with "electrical state".QuoteThat's an easy one: 0The mass however remains the same.Dave

author: Brutte
author_rank: Frequent Contributor
timestamp: June 07, 2019, 11:08:36 am
content: The switch stays NO "normally open" no matter if you actuate it or not. It is a property of a switch and not its (electrical) state. So if you actuate a NO switch, the switch is still "normally open", although the switch starts conducting.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 07, 2019, 11:59:12 am
content: Quote from: brabus on June 07, 2019, 09:11:08 ammanually actuated switches such as toggle switches, DPDT SPDT etc dont usually specified as NO nor NC. non-latched or returning switches are seldomly in use. so anyway, there are many type of switches, the person who made this question should take this into consideration. C is possible as well as D. the OP should also ask the teacher why it cant be D to understand his rational.

author: Rerouter
author_rank: Super Contributor
timestamp: June 07, 2019, 12:17:04 pm
content: When ever I feel like a question is ambiguous I just write my assumptions next to the answer,Another Agreeing with D as the most correct answer given the assumptions, for the next one, a solar panel would be the most correct, as its the device generally used for that purpose. e.g. the lay person answer.Back when I was studying electricity in TAFE, There where a few tests where the teacher had obviously had his own go at rewording or answer flipping the reference test to try and catch people who found a copy of the previous years one, sadly he introduced a ton of typos and made some things really hard to answer,I did win him over to revising the next years test with my suggestions, but that was more or less earned respect, as I tried to not be a dick about it, and he knew I was smart on the topic,Best memory of that class was creating a washing machine ladder-logic solution, I solved it in about 4 minutes, had 30 minutes to do it, so iterated it down to the least relays and function blocks possible, It for one flagged any other student that had (tried to) copied me, and left the teacher needing to simulate the thing to make sure it worked as he could not follow it. was a fun task,

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 07, 2019, 06:35:15 pm
content: Another vote for D.They label the "Normal" positions when the switch isn't activated. So NC will connect to common (C) , and NO will be floating. Once the switch is operated, the NC is disconnected, and NO is connected to common.Look at page 2 of this datasheet.http://www.farnell.com/datasheets/1702886.pdfEDIT : And as applies to Relays-https://circuitdigest.com/article/relay-working-types-operation-applications2nd EDIT : "In schematics switches are always drawn in the OFF position."http://www.zen22142.zen.co.uk/Prac/relay.htm

author: Nominal Animal
author_rank: Super Contributor
timestamp: June 07, 2019, 08:05:48 pm
content: CoopedUp: If I were you, I'd find a SPDT switch with NO and NC markings (any common microswitch, or say a wall-mounted light switch), and show it to the teacher:These markings only make sense on an electrical switch when NO and NC represent the state when the switch is not actuated. Whether there is current flowing/power applied or not, has nothing to do with the switch (unless the power is enough to break the switch); the switch controls the electrical connection. Thus, D is the correct answer.Someone mentioned relays; they too have NO and NC markings:However, for a relay, "actuated" state == "energized" state == "when power is applied"to the relay coil; and "normal" state is when there is no power applied to the relay coil.Whether there is current flowing over the NO/NC pins or not, is irrelevant. So, D is definitely still correct; C (power is not applied) is only correct if we amend the"when power is not applied"with"to the relay coil". Otherwise there is ambiguity inwherepower is applied with respect to the relay.In every single case, whether power is conducted through the connection controlled by the switch or relay, is completely irrelevant.My instincts say that your teacher is in error, because they are fixated on looking at things from the point of view of controlling the current/power, instead ofcontrolling the electrical connection. If I were you, I'd start my objection with something like"that might make sense if you looked at from the point of view of controlling the current/power, but in reality, a switch controls the electrical connection, and not the current or power conducted through the connection", followed by the images and text above.We need to learn how correctthe utterance or writing, instead of theperson making it, because you are at a common task, not adversaries.This sounds silly social games, but it is important nevertheless. It means you acknowledge that perhaps the person isn't wrong, and is simply expressing themselves poorly. It means that you do not question their knowledge, simply the way they express it. Mis-expressing stuff is, in my experience, much more common than being straight-out wrong, at least when talking with professionals.That approach to error-correcting is fortunately very contagious, and rapidly spreads: wefeelbetter when our output is criticized and made better, without criticising us ourselves as a person. It also helps the lecturer, as correcting errors have much less impact on ones self-esteem, as it is questioning thewaythings are put, rather thanthe knowledge it stems from. I've been on both sides (student and lecturer), and it definitely works well for me.This is also why I use a pseudonym on the intertubes: it reminds me that any and all criticism is based on my work product, and has nothing to do with me as a person, as none who use that pseudonym know me socially. (As a self-broken husk of a man, I need that sort of a social crutch.)

author: Brumby
author_rank: Unknown
timestamp: June 08, 2019, 02:27:54 am
content: From the outset, I've dismissed any answers where "power" is mentioned as a condition. As a couple of others have said, thestateof the switch contacts in their "normal" position is not defined by whether power is, or is not, applied. It is defined by a physical property when examined in isolation.The answer is D - but if the teacher has a different one in mind, I'd like to hear their reasoning.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 08, 2019, 05:25:01 am
content: NO & NC areby convention, in the unoperated state of the device, & do not depend upon the external circuit.The other interpretations are misunderstanding at best, & sophistry at worst.

author: StillTrying
author_rank: Super Contributor
timestamp: June 08, 2019, 06:02:40 am
content: "The abbreviations NO (normally open) and NC (normally closed) represent the electrical state of switch contacts whenC. power is not applied."That makes no sense, is 100% wrong, ambiguous, and stupid, if they meant relay they should have said relay and not switch, and even then it should say coil somewhere. The OP should buy the teacher a hat with the correct answer on it.Just a picture of one of those micro switches above with C, N/O, N/C on it would do. The explanation of where power comes in to it won't make any sense, so keep his new hat ready.

author: tautech
author_rank: Super Contributor
timestamp: June 08, 2019, 07:54:49 am
content: Quote from: StillTrying on June 08, 2019, 06:02:40 amThis^^^Teachers like to think they know everything and therefore occasionally need to beresetto show they arenotinfallible and in fact human and mistake prone like anyone else !These are good examples of poor teaching skills and appropriate to take to the head of department for their correction of the syllabus.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 08, 2019, 09:48:11 am
content: Quote from: tautech on June 08, 2019, 07:54:49 amteaching skill is different from making question skill. syllabus is another thing made by another body. good teacher will encourage students to learn and accepts mistake incase student or anybody else highlight it. its more personal matter. i was lucky to get into some program to allow "non-education specialized course graduate" to enter education sector. i saw many of these "education specialized course" young teachers lack practical implementation of the syllabus they taught. but many from them are quite tolerant. stubborn teacher is quite rare though, its something they are taught in college? or just personal matter i dont know, but i believe its personal matter. i wish from time to time they will allow again "non-education specialized" such as from engineering, doctor, accountant degree course to become teacher so various discipline can share thoughts for better education.Quote from: StillTrying on June 08, 2019, 06:02:40 amso it mustn't be atransistor? he should call it an "electromagnetic coil actuated switch" not a relay, because relay means...https://dictionary.cambridge.org/dictionary/english/relayyou cant apply power to nor "actuate" a group of people, its illegal.. well literalism hat off...

author: soldar
author_rank: Super Contributor
timestamp: June 08, 2019, 10:43:14 am
content: Quote from: DimitriP on June 07, 2019, 09:45:35 amIf a man talks but his wife is not there to hear him, is he still wrong?

author: Cerebus
author_rank: Super Contributor
timestamp: June 08, 2019, 05:25:44 pm
content: Quote from: soldar on June 08, 2019, 10:43:14 amI've checked with the Mrs. and the answer is "Yes".Back to the, according to the Mrs., much less important issue of the two questions presented as examples.If the person who set them can't see why they are very badly written questions then they should be sent off for some remedial education themselves. If they actually know that they are terrible questions, but insist on still defending themselves to their students when they point out the inadequacies of those questions they should get the hell out of education as a career. Still claiming to be right, when proven wrong, is a disqualifier for almost any occupation except hermit or politician.

author: Nominal Animal
author_rank: Super Contributor
timestamp: June 08, 2019, 06:09:44 pm
content: I agree with what Cerebus wrote above, even though I recommend a softer initial approach.That is, I still believe one should start with the assumption that it is a miscommunication and not an error. Doing that in my experience makes others do that too, and therefore the quality of the information exchange rises, and that is excellent value for small effort. Me fail English often myself when I get excited or tired, and no matter of remedial education seems to fix that. However, when the error isproven(as it has in various posts in this thread), refusal to correct that error meansnothingthat person says can be taken at face value anymore.

author: bson
author_rank: Unknown
timestamp: June 08, 2019, 06:13:14 pm
content: Quote from: exe on June 07, 2019, 09:02:08 amIn a sense yes, but it's also about reading comprehension, paying attention to detail, and context. Such as,what is a switch. A switch closes two contacts. In the absence of other information, that is what a switch is. Hence, C or any other talk of applying power is irrelevant. A relay is a coil-actuated switch, but there is no talk of coils or relays here. Just a switch. Nor do coils or power need to be introduced to answer the question. Questions like this teach students to work with the information provided, not go off and imagine something other than what's actually stated. This is a critical cognitive engineering skill, because 99% of the time PMs will come with a poor explanation of a problem that requires clearing up before proceeding to find a solution, along with a proposed solution (that should be courteously accepted but doesn't need to make it further than your inbox). It's a pretty basic critical reasoning skill.

author: ebastler
author_rank: Super Contributor
timestamp: June 08, 2019, 07:13:20 pm
content: Quote from: exe on June 07, 2019, 09:02:08 amYeah, or even better: "What is the normal state of a normally open switch?"The standards at school are not quite that low, I think...

author: soldar
author_rank: Super Contributor
timestamp: June 09, 2019, 11:49:12 am
content: Quote from: ebastler on June 08, 2019, 07:13:20 pmHow about "You are asked what is the normal state of a normally open switch, can you check 'open' in the choices given to the right?"

author: Psi
author_rank: Super Contributor
timestamp: June 09, 2019, 11:53:01 am
content: Yep, question is trying to confuse you.Need to read it carefully and not jump to any conclusions.That's pretty common with multichoice questions.When creating multichoice questions the test writer has to be careful they don't give away the answer by simply having it as an option.So they make it a bit confusing and have multiple correct answers and you have to carefully figure out what exactly the question is asking.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: June 09, 2019, 10:50:11 pm
content: Ok, I will throw my 2 cents into this discussion, since I have been a successful electrical engineer since well before the turn of the century. The use of the word "power" is ambiguous in nature, since power is a measure of watts. However, even if the question used the term EMF or Voltage, it does not apply in the case of the syntax of the question. So, all answers with the word "power" in them are ambiguous. Further ambiguous is the term in question "electrical state", which NO and NC does not apply to any electrical state when a switch is normally open or normally closed. NO and NC apply to the physical condition of a switch that is not actuated, period, whether it is a relay or a manual switch. In the case of a solid state relay, the same is true, even though the active part of the switch is not a contact. As someone earlier posted, there are conditions that are spelled out on the schematic where a switch can be NO, but held closed on machinery, and the same with NC, held open, but this is not even in the ballpark of the syntax of the question.The abbreviations NO (normally open) and NC (normally closed) represent the electrical state ofswitch contacts whenA. power is appliedB. the switch is actuatedC. power is not appliedD. the switch is not actuatedBTW, my answer would be "D." in all cases.Hope this helps...EDIT: If voltage is not applied, there is no "electrical state", just sayin'.

author: jmelson
author_rank: Super Contributor
timestamp: June 09, 2019, 11:35:59 pm
content: Quote from: CoopedUp on June 07, 2019, 03:05:14 amForget everything you learned in this class (unless you can verify it elsewhere), this guy doesn't know what he is talking about.if this is a university or tech college, report this to higher ups, it really is not good that he is giving his incorrect understanding to a class full of students.If you want corroboration, look up switch info on a manufacturer's web page, the makers of switches have been using this terminology for well over 100 years! Or, see :https://en.wikipedia.org/wiki/Switchin the section on "Contact terminology". They correctly state that the NO or NC designation has NO reference to POWER, but only to whether the contacts are touching or not touching!Jon

author: DimitriP
author_rank: Super Contributor
timestamp: June 10, 2019, 12:50:06 am
content: QuoteDear everyone, the question as posed ( whether it's an appropriately phrased for the intent or not ) includes the magic phrase "electrical state".Everyone that says D, is not answering the question as worded, but answering the "intent" of the question instead.Out of the four possible answers, there is only one single, solitary, lonesome answer that involves the "electrical state" of the switch and that's when electricity is present.No electricity, no electrical state.Either way in my book it justifies a "your question doesn't mean what you think it means" tshirt .

author: pwlps
author_rank: Frequent Contributor
timestamp: June 11, 2019, 02:02:41 pm
content: Quote from: DimitriP on June 10, 2019, 12:50:06 amI agree, still it would need some more training in the scholastic disputatio techniques for the OP to convince his teacher. As others stated if we replace C by "power is not applied to the switch actuator" then C and D would be equivalent but with the actual formulation C is ill-defined because we don't know where the power is applied. Yet we could argue it is still equivalent: if power is turned down in the Universe then the switch will stay in it's "normal" position for sure. But then there is no way to define any "electrical state" ...

author: Brumby
author_rank: Unknown
timestamp: June 12, 2019, 03:08:38 am
content: Quote from: DimitriP on June 10, 2019, 12:50:06 amI disagree.The physical state would involve a description of a device's physical characteristics - size, weight, component materials, even colour. The electrical state would involve a description of a device's electrical characteristics - connectivity, resistance, inductance.In the case of a switch, it's electrical characteristics are related to its physical characteristics. Where the switch is in one position, there will be an electrical connection and when it is in the other, there will be no electrical connection.Thus, for a NO switch to be physically in its rest state, the electrical state will be: open circuit.For a NC switch to be physically in its rest state, the electrical state will be: short circuit.However, if we were to interpret the phrase "electrical state" correctly for this situation, we should examine thelevel of educationwhere it has been presented and in thecontext of the learning already offered. For example: Is it a phrase in a PhD thesis where semantic accuracy is crucial -or- is it simply a phrase to express whether a switch will pass current or not? Imagine Sheldon Cooper teaching 4 year-olds the physics of building sand castles.Quote from: Psi on June 09, 2019, 11:53:01 amThis is one aspect of multiple choice questions that cannot be overstated.However, I have aMAJORbone to pick with the wholeideaof multiple choice questions: They do not represent a relevant and fair test of the examinee's knowledge. There are two aspects of significance:1. It is almost universally true that you will never come across a real world situation where there will be three or four potential solutions offered to you where one will be correct. You will be presented with a situation that may not have any clues as to what your options are. You will just need to know your stuff.2. Often, you can deduce the correct answer by eliminating wrong answers. When those wrong answers are obvious and/or silly, what does the question prove? All it will do is decrease the odds of a guess being correct. I will admit, though, that in some cases this will be useful as there could be one or more "wrong" answers that aren'tobviouslywrong and will need greater thought. This is one such case - but the care needed to phrase the question and answers with clarity is paramount. We do not have consensus that this has been achieved.