AC Circuit Qs: Power & Current w/ 200V RMS

[dhruv.tara]

Now this is not a homework question, just a practise question and my answer doesn't match.

An AC source of 200 V rms supplies active power of 600 W and reactive power of 800 VAR. The rms current drawn from the source is ? (the answer is 3.75 while mine is 5)

I did was squared and added the powers to get V^2*I^2, plugged in the value of V and got I as 5... Any help?

 

[vk6kro]

I like your answer.

Try it with 24 ohms resistive and 32 ohms reactive in series.
I squared R:
5 * 5 * 24 = 600 watts
I squared X
5 * 5 * 32 = 800 VAR

resultant of r + x:
SQ rt of (24 * 24 + 32 * 32) = 40 ohms
200 V / 40 ohms = 5 amps

 

[muh_j18]

p=sqrt(3)*V*I*p.f

 

[dhruv.tara]

from where did that sqrt(3) factor come into? I have seen this factor before, but as far as I remember that was in 3 phase systems... And I am not dealing with such problem yet I think...

 

[muh_j18]

sorry, my mistake, you're right dump the sqrt(3).

 

[dhruv.tara]

hmm okiess... thanks all