I am a student at Penn Foster Career School and i am having a problem with a question and need a little help...plz.... the question is: the output of a power supply is measured at 12v with no-load connected. the manufacturer's specifications say the power supply has a regulation of 10%. What is the full-load output voltage of the power supply?

A. 13.2v C. 10.8v
B. 10.9v D. 1.2v

I answered C.10.8v and was told that i was wrong i have a retake of this test in a few days and dont want the answer given to me just want to try to understand a little better i am leaning to D. 1.2v because i took the no load voltage and multiplied by 10% and came out with 1.2 and this is what i did the first time but then subtracted 1.2 from 12 and came out with 10.8.. i think i am confused or i am thinking further than i need to

thanks in advanced
Dean

I would have chosen "C" too. Guess I need to go back to school.

Originally Posted by dnolan747

I am a student at Penn Foster Career School and i am having a problem with a question and need a little help...plz.... the question is: the output of a power supply is measured at 12v with no-load connected. the manufacturer's specifications say the power supply has a regulation of 10%. What is the full-load output voltage of the power supply?

A. 13.2v C. 10.8v
B. 10.9v D. 1.2v

I answered C.10.8v and was told that i was wrong i have a retake of this test in a few days and dont want the answer given to me just want to try to understand a little better i am leaning to D. 1.2v because i took the no load voltage and multiplied by 10% and came out with 1.2 and this is what i did the first time but then subtracted 1.2 from 12 and came out with 10.8.. i think i am confused or i am thinking further than i need to

thanks in advanced
Dean

Dean.

This is not an "intuitive" thing to understand, because the answer seems so obvious, but the answer is 10.9.

Are you aware of the formula?
Google voltage regulation or better yet full load voltage.

I would have answered it as you did without knowing the formula.

edit:

actually I got 10.09, which doesn't make sense.

Bear with me.

OK.

As I said, I had never needed to use this formula, but judging by what I see, something is missing here.

Are you stating this question from memory or are you typing it verbatum?

Are you sure you didn't get it backwards, ie the 12 volts is the value under the load and you are supposed to find the no load value?

i do know the formula if this is the one you are speaking of which is: %voltage regulation=Vnl minus Vfl divided by Vfl multiplied by 100 or
%voltage regulation=Vnl-VflX100
Vfl
but how do i convert this formula to do what the question is asking me????? I know the no load is 12v and the percentage of regulation is 10% so how do i get the full load voltage value????

the Vfl was supposed to be under the Vnl-Vfl but is was somehow put all the way to the left but i think yall will understand where i was going with that

Are you stating this question from memory or are you typing it verbatum?


i am copying it straight out of my text manual

Originally Posted by ke5frf

OK.


Are you stating this question from memory or are you typing it verbatum?

i am copying this straight out of my text manual

I got 10.9.

10 = (Vnl - Vfl)/Vfl*100

After some algebra:

Vfl = Vnl/(10/100 + 1) or

Vfl = 12/1.1

= 10.9

no the test is not timed in fact it is open book but i guess where i am having the problem is that it is a home course and the biggest problen is i have a problem with algebra... but i am trying to overcome this I thought this home course would be easy but i think i just reallized that an instructor standing at the front of the class is much better.....i am still not seeing where yall are getting the 1.1 in the algebra part but thanks for all of yall's help and i will go back and study the algebra part of that post

Dean

1) divide both sides of equation by 100. - result 10/100 = (Vnl - Vfl)/Vfl
2) Multiply both sides by Vfl -result 10/100*Vfl = Vnl - Vfl
3) Subtract Vfl from both sides -result 10/100*Vfl + Vfl = Vnl
4) Factor Vfl from lest side -result Vfl(10/100 + 1) = Vnl
5) divide both sides by the factor in step 4. -result Vfl = Vnl/(10/100 + 1)
6) solve -result Vfl = 12/1.1

You're rally going to need to be able to do work like this to do electronics.

Originally Posted by BrownOut

You're rally going to need to be able to do work like this to do electronics.

yes i know that i will need to be able to do this,,, i am just having a hard time with this i think because this is an at home and online course and i do not have an instructor in a classroom setting and it has been 15 years since i graduated high school and that long since i had an algebra course....but anywat thanks brownout i think that brought a little of it back... my brain is on overload!!!!!!!!!!!!!