# not sure about Vrms (my exam question)

Discussion in 'Homework Help' started by STUDENT_LV, Aug 13, 2007.

1. ### STUDENT_LV Thread Starter New Member

Aug 13, 2007
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a cirucit in full wave rectifier.

from the V primary , they give Vac suppy 110v. nisbah 2:1

Vsec = i use the vac suppy to 110/0.707 then use the nisbah to find the vsec ritE? Vrms for my sch = 0.707 i wan to know is i need to use Vrms or not ? get wat i mean ? my english very poor >< must reply me pls. important for the mark

2. ### recca02 Senior Member

Apr 2, 2007
1,211
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u shud be studying the topic,
if u cant answer that it means u shud study harder,
one question
do u know the turns ratio

3. ### amit_eie New Member

Aug 15, 2007
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Vrms means Root Mean square value.
Vrms=0.707Vm,I suppoese Vm =110,then calculate result.plz put your question in more details so that i can help you.

4. ### RiJoRI Well-Known Member

Aug 15, 2007
536
26
Comment: if someone states his or her English is very poor, using abbr.s lk shud dsnt help 'em A-TALL!

Student_LV: the English word for "nisbah" is "ratio." Mains voltages are given in RMS, unless otherwise stated. So, given an input of 110Vrms, with a ratio of 2:1, the transformer's output would be 55Vrms.

I trust this helps!
Regards,
--Rich

5. ### techroomt Senior Member

May 19, 2004
198
1
please don't come in a' blastin', i'm sure there was no intent there.

any voltage value (p-p, peak, avg, rms)can be applied to the transformer turns ratio, you just need to be consistent using the same for "in" as you do for "out".

6. ### recca02 Senior Member

Apr 2, 2007
1,211
0
oh i m sorry, i will take that into consideration next time its just a bad habit i shud improve on
and yup as MR techroomt said any value can be used in eqn the answer will be in that form (need we even mention that?)

Student_LV: it is also true that voltages are generally specified in terms of Vrms (as stated) unless stated otherwise however for academics always state your assumptions in the answer.