Capacitor blocks DC supply

[Vivek Chandran]

Why capacitor blocks DC supply?

 

[paofanello]

The question is not "why", but "how".
Probably you have to real study what is a capacitor, first.
https://en.wikipedia.org/wiki/Capacitor#DC_circuits
https://www.explainthatstuff.com/capacitors.html
https://electronics.howstuffworks.com/capacitor.htm

 

[D.A.(Tony)Stewart]

Capacitor is an insulator as are all dielectrics. ( vs Conductors)

So it depends on if it is in series or parallel.

 

[KD494]

A capacitor is two conductive plates separated by an insulator. DC doesn't flow very well through an essentially open circuit.

As far as explaining it with equations, the current through a capacitor is:

Ic = C * (dv/dt)

No changing voltage means no current through the component.