What??? Not 100???

[straynote6]

The "so called instructor" is me and based on your answer, I would give you an F as well.

 

[straynote6]

180 Degrees

180 Degrees

The aforementioned student has recently gained my respect immensely. Not only does he show me respect (whether I deserve it or not), but - to be point blank - he is like a new man. Or maybe I've changed, I don't know.

He is one of the most gifted students I have - very bright and very willing to learn. He always asks great questions and now challenges me to step up to the plate and try to become a better teacher.

Hats off to John (not his real name, of course). Should the time ever arise, I'd gladly buy you a jar of suds. Keep pressing on.

 

[Strife]

Was he wrong?
Semantically : I guess.
Overall, as an understanding to the concept? maybe he was ahead of himself.

As far as the second part. I'd kick him out of the class, no matter how smart he was.
Hitler was a genius. Doesn't make it right what he did.

Strange as it may seem, last night I had a student verbally (and out loud) challenge me about a question I marked wrong on his test.

The question: What is the formula for Apparent Power?
Correct answer = Papp = IV
His answer: IV

I marked it wrong and he became livid. Shouting profanity laced comments.

Was I wrong and too critical?

By the way, his final test score was 99%.

 

[Strife]

Huh?
The power formula is the same no matter the voltage.
the voltage formula for a single phase VS a three phase is different.
As in 3PH V = 1Ph V * "square root of 3" * "angle factor"

The question asked for a fomula, not an equivalent factor. Technically, the answer was wrong.

That said, the question was inadequate, in that it did not say whether you were asking about a single phase or three phase system. Your answer is right for a single phase system, but your answer was only half right, since there were two possible answers.

 

[K8MHZ]

The aforementioned student has recently gained my respect immensely. Not only does he show me respect (whether I deserve it or not), but - to be point blank - he is like a new man. Or maybe I've changed, I don't know.

He is one of the most gifted students I have - very bright and very willing to learn. He always asks great questions and now challenges me to step up to the plate and try to become a better teacher.

Hats off to John (not his real name, of course). Should the time ever arise, I'd gladly buy you a jar of suds. Keep pressing on.

He must have read post #43.



Glad to hear that it worked out well.

 

[mlnk]

The "so called instructor" is me and based on your answer, I would give you an F as well.

My answer would be:
The formula for apparent power, S, is:
S= the square root of ( P squared + Q squared)
measured in VA
P = true power measured in watts
Q = reactive power measured in VAR
This shows you that apparent power is a larger number than true power( unless Q is zero) and how we arrive at apparent power. It also leads to the topic of vectors/triangles.
IMHO, Papp=IV can confuse a student because real power is volts x amps, so what's the difference?
Could you please do some research on the accuracy of my answer and change my grade to "A"?
Incidentally, the "so-called instructor" is me-I constantly learn from students and other instructors in the quest for perfect test questions.

 

[straynote6]

My answer would be:
The formula for apparent power, S, is:
S= the square root of ( P squared + Q squared)
measured in VA
P = true power measured in watts
Q = reactive power measured in VAR
This shows you that apparent power is a larger number than true power( unless Q is zero) and how we arrive at apparent power. It also leads to the topic of vectors/triangles.
IMHO, Papp=IV can confuse a student because real power is volts x amps, so what's the difference?
Could you please do some research on the accuracy of my answer and change my grade to "A"?
Incidentally, the "so-called instructor" is me-I constantly learn from students and other instructors in the quest for perfect test questions.

Hi Mink

Your answer may or may not be correct and it's really not the point. We teach from a specific text book, so the answer is always RELATIVE in that context, whether I agree with it or not.

I applaud your enthusiasm and encourage more challenges to your teachers, whoever they may be. Good luck!

 

[mlnk]

If the textbook is misleading, it should be corrected. I think most of us experienced instructors are at the same level as the writers of textbooks--so do not be afraid to challenge the text. The instructor should show the student how to do research to find material that helps you pass tests, succeed on the job, and not get electrocuted!

 

[Besoeker]

My answer would be:
The formula for apparent power, S, is:
S= the square root of ( P squared + Q squared)
measured in VA
P = true power measured in watts
Q = reactive power measured in VAR

With respect, I think that is totally out of context with the original straightforward question.
We all know, or should, that the apparent power is the product of voltage and current. To determine real and reactive components power factor to be included, either declared or measured and a calculation. But that wasn't the question asked.
A good piece of advice is answer the question you were asked, not the one you think you were asked.

IMHO, Papp=IV can confuse a student because real power is volts x amps,

It is for DC but the question was about apparent power and that should clue you in that the question is clearly in reference to AC circuits.
Real power is thus Volts x Amps x power factor. And times sqrt(3) for a balanced three phase circuit.
Miss that out and you get awarded a wrong answer.

so what's the difference?

Power factor, obviously.

Could you please do some research on the accuracy of my answer and change my grade to "A"?

Not a cat in Hades chance........