Answer / sujin

For a dc signal frequency is approximately 0.
For a capacitor reactance ( Xc) is 1/2*3.14*f
Since f is or approximately 0 Xc= infinity.
Hence it blocks dc current

Answer / manishsingh

i=C(dV/dt)
for dc instantaneous change in voltage=o
dV/dt=o
...i=o for dc supply mens no current..

so capacitor block dc supply

Answer / bhabani

capacutive reactance is inversely proportional to frequency.
for dc f=0.thus very high reactance to current

Answer / devsingh boda

ANS1,ANS3,ANS4 are correct.ie,
We can answer this question in two ways,
1.Capacitive reactance is inversely proportional to frequency since,Xc=[1/(2*Pi*f*C)] which implies Xc is inversely proportional to f. For dc f=0 , so Xc is approximately equal to infinite(very high).So current does not flow.

2.We know that capacitive current, Ic=C*[dVc/dt]...
If dc supply is applied across capacitor then dVc/dt becomes zero since dc voltage is a constant(steady) voltage.So Ic also becomes zero.

Answer / shahbaz

because the capacitor is used to store the charges and in
const supply there is no any storege is carried out hence
ckt is not complete.

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