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Chima Sunday (Tutor)
16-02-2016 14:19:00 +0000
The opposition to current flow due to resistor presence in a circuit is called Resistance. When inductor or capacitor is present in a circuit the opposition it offers (i.e capacitor or inductor) is what we call Reactance. Consequenty, we have Capacitive Reactance which is the opposition to current flow due to capacitor in an a.c circuit. it is represented thus (Xc = 1/2πfc), where c = capacitor measured in Farad(F) and f = frequency measured in Hetz(Hz). And Inductive Reactance which is also an opposition to current flow when an inductor is present in an a.c circuit. It is reresented thus (XL = 2πfl), where f = frequency measured in Hetz and l = inductor measured in Henry(H). Since both XL and Xc opposes current flow, there units are still in respect of George Ohms(i.e Ohms)
So in a typical question where you are ask to find Capacitive reactance Xc when f and c are given. Also same for Inductive Reactance XL, when f and l are given. As we will see in the following examples
(1)An inductor of 0.012H is connected to an a.c circuit of frequency 140Htz. Calculate the reactance of the inductor. (π = 22/7)
recall that reactance of the inductor = XL = 2πfl
here l = 0.012H, and f = 140Hetz
so XL = 2×22/7 × 0.012 × 140 = 10.6 ohms
(1)In Nigeria, a.c supply is in frequency of 50Htz, if this same inductor above is connected to an a.c circuit of Nigeria kind frequency, Can you calculate the reactance of the inductor?
(2)What of if the same circuit is connected to a capacitor of 8 micro Farad. Can you calculate the reactance of the capacitor?