I have the following problem and I'm not sure if I did it correct:
Given v(t) =10 + 5 Sin (377t+30 degrees) - 7 Sin (377t-45 degrees)
Find VRMS
Putting them into rectangular form:
(7.07 + j 0) + (3.06 + j 1.77) - (3.5 - j 3.5)
now I add my reals and imaginaries and that's my answer? Or I can convert that number into polar as well.
sounds like homework to me sonny..
sQuick..
and? I'm asking a question so I can understand it better. I've done half the problem already!
You have also gotten the wrong results for that half. You may understand the concept of polar to rectangular conversion, but your trigonometry math is wrong. It helps to draw your vector, then the real and imaginary sides of the triangle and do the math from there. Show all work. You have another mistake but I'm not going to tell you what it is.
Back in high school trig (college prep track 1978-79), Mrs. Fliegel made us memorize sine, cosine and tangent at 0, 30, 45, 60 and 90 degrees. We also had to draw them freehand on trig graph paper. Calculators were not allowed in that class!
Mike
The first term looks like a dc term.
Bill
-- Ferme le Bush
You cannot use phasor since you have a DC component.
Recall that RMS = root-mean-square.
Therefore, to obtain Vrms first calculate the square of v(t), i.e. [ v(t) ]^2. Then integrate the result over one cycle, i.e., from t=0 to t=1/(60), and then divide the result by 1/(60) to obtain the mean. Take the square-root of the result. The answer is the Vrms.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required