Question

RMS current in an AC circuit is 2A. If the wattless current is 3^1/2 A, what is the power factor?

Answer 1

Watt less current is the current if there was absolutely no resistance!

Answer 2

So.... the answer is...

Answer 3

so can u build up on my hint ? :P

Answer 4

Actually, I haven't studied the chapter properly. Also I don't have much time. Please, if you know the answer the tell me. Thanks

Answer 5

sorry.. that way you won't learn
And unless you study the chapter how can attempt the question?.. i advice you to go review your textbook or course handout or something

Answer 6

If by "wattless" current you are referring to reactive current then the power factor would be the ratio of the squared value of each type of current as power is equal to I squared R and VARS (Reactive or imaginary power) is ! squared Reactance. Power factor is the cosine of the phase lag between current and voltage.

Answer 7

@Mashy According to your hint, wattless current is the current if there was absolutely no resistance. So power factor, cos{phi} would be equal to R/Z = 0? Is'nt it right?
But the answer is not there in the option! That is what is making me confused.

Answer 8

no.. u are calculating power factor for pure inductance case...which is obviously zero!!

using the wattless current, calculate the inductance will ya.. (in terms of Vrms, ultimately Vrms would cancel out)

Answer 9

There is some confusion here. If there was no resistance, then current would be inifinite for any amount of applied voltage. Not understanding the term "wattless" current. Is that suppose to be the square root of 3?? "3^1/2"

Answer 10

@radar Yes, it is given wattless current is the square root of 3. I think a current that requires no power is called wattless current. So what you said (i.e reactive component of current is wattless current) is right.