1. A resistor and a capacitor are connected in series to an ac voltage source (f

Question

1.     A resistor and a capacitor are connected in series to an ac voltage source (function generator).The source provides

an instantaneous voltage of V(t) = Vm sin (2pft) at a given time t. Let subscripts R and C represent the resistor and the

capacitor when applied to a current or voltage symbol.

a)     (2 points) Is the relation V = VR + VC , where the voltages represent rms values, applicable?

b)    (2 points) What does Kirchhoff's voltage rule say about this circuit?

c)     (2 points) Is VR in phase with VC? Explain.

d)    (2 points) How is the capacitive reactance XC related to VC? Give your answer in an equation form.

e)     (2 points) How is the capacitive reactance XC related to the frequency f of the source voltage? Give your answer in an equation form.

Explanation / Answer

a) the relation V = VR + VC , where the voltages represent rms values is not applicable because the voltage of the capacitor is not inphase with the resistor's voltage..

b) Kirchoff law is applicable for this circuit. It's just that the equation will contain integration of current while writing the voltage across the capacitor... Kirchoff's law is absolutely valid for this circuit..

c) VR is not in phase with Vc.. in fact VC lags VR

d) The relation is linear.. Vc = Ic * Xc , where Ic is the current flowing through the capcitor.

e) Xc = 1/(2*pi*f*C), so it is inverse to frequency..

Thanks ,, Comment if you need more explanation..

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