Question : How does one calculate Xc when the capacitance is not known ? [ 2 unknowns in the equation].
Thanks, Jack
Thanks, Jack
Sounds like homework. Is it?Question : How does one calculate Xc when the capacitance is not known ? [ 2 unknowns in the equation].
Thanks, Jack
Okay, good start. Please continue through the next steps.One method might consist of placing a resistor in series with a capacitor. Then apply an AC voltage across the two components, in series. The next productive step is to correctly visualize the mathematical arrangement of the two elements. They are in series, however, one component is mathematically real, and one component is mathematically imaginary.
Thank you; With your help, I'll attempt to answer my question.The capacitive reactance is going to be the voltage across the capacitor divided by the series current. The series current is the current going through the resistor ... a real quantity, easy enough to calculate ... voltage drop division by resistance.
... The capacitor voltage, call it Vc, is going to be a result determined using the Pythagorean Theorem. The hypotenuse of the triangle is the total applied voltage, Vt. One known side of the triangle is a voltage measurement across the resistor, Vr. The unknown side of the triangle is Vc.
\(V_T^2=V_C^2+V_R^2\)
... You have found Vc and Ir.
Depends on the test, but it certainly could. Also, you need to consider whether the test results would have any meaning whatsoever.Would a short-term test using AC on an electrolytic cap destroy it ?
Jack
by Jake Hertz
by Jake Hertz