Electronics > Beginners
Trying to prove a point
soldar:
--- Quote from: ebastler on June 08, 2019, 07:13:20 pm --- Yeah, or even better: "What is the normal state of a normally open switch?" :P
--- End quote ---
How 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?"
Psi:
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.
tpowell1830:
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 of
switch contacts when
A. power is applied
B. the switch is actuated
C. power is not applied
D. the switch is not actuated
BTW, my answer would be "D." in all cases.
Hope this helps...
EDIT: If voltage is not applied, there is no "electrical state", just sayin'.
jmelson:
--- Quote from: CoopedUp on June 07, 2019, 03:05:14 am --- :blah: 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
--- End quote ---
Forget 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/Switch in 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
DimitriP:
--- Quote ---The abbreviations NO (normally open) and NC (normally closed) represent the electrical state of
switch contacts when
A. power is applied
B. the switch is actuated
C. power is not applied
D. the switch is not actuated
--- End quote ---
Dear 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 .
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