If a capacitor blocks d.c. and passes a.c what happens if a varying d.c signal is applied.
As it is still d.c , is it blocked ? . If not then is it right to say a capacitor only blocks constant d.c

Thanks

 

The AC component of the varying DC is passed. That is a normal use of a capacitor, to block the DC and just pass the AC signal.
And really, a varying DC is DC with AC superimposed.