# Capacitor as Noise removal (Theoratical)?

I am reading about the capacitors. I have read that the capacitors block DC and behaves as open circuit in DC while short circuit in AC. The reason behind this is the charging and discharging of the capacitor. What is my perception about it, I will mention about it.

" During the DC voltage the capacitor charges up. During this charge process the negative charges from the battery comes in the wire and then get store on the plates and on the positive side there is a deficiency of charges on the plate as the electrons are attracted by the positive terminal of the battery. Due to this deficiency of charges an Electric field is generated that opposes further movement of electrons towards the positive side and stop the excess amount of electrons on the negative plate side. When this potential strength is equal to battery potential then the the impact is neutralized and no further movement happened and thats where the electrons started flowing on the other path and capacitor behaves as open circuit"

Now for the noise filtering capacitor they are actually connected for noise removal so that the current can safely go out. It makes sense that the noise in the form of sudden spikes comes from power supply. What I am confused is the statement about the capacitor behavior for this sudden spikes. I have read the capacitor gives the path of the Ground towards sudden spikes which is according to me is utterly wrong. Because no electrons pass through the dielectric material.

According to the above explanation for the DC voltage, the capacitor is in stable state. If the sudden spikes of voltage come in (Obviously High Frequency) then the equilibrium of Electric field between the plates and voltage is disturbed and capacitor started charging again with the access charge (More electrons come in from the negative side and more positive charges or electrons departure from the positive plate). But when the spike is over the capacitor is required to discharge in order to reach to that equilibrium again. Now there are two ways of going back towards equilibrium. 1) If the capacitor negative plate loose electrons and positive plate gain some electrons (This is not possible) 2) If the electrons cross the dielectric and reach towards positive terminal of the battery (This is again not possible)

My logic is not conventional flow, it is electron flow. May be I am totally wrong but please help me to solve this dilemma.

• Electrons my not physically cross the dielectric, but the arrival of electrons on one plate of the device will displace electrons on the other plate. We now have electrons moving, a definition of current flow. – Peter Smith Feb 23 at 14:59
• All noise-filters are actually voltage-dividers, with a series component that has HIGH_impedance (perhaps a resistor), that followed by a shunt LOW_impedance (perhaps a capacitor). At higher frequencies, the capacitor's charging currents cause most of the input voltage to be wasted across the Series impedance, making the capacitor's voltage be very very low; this voltage-division action provides the 'filtering'. – analogsystemsrf Feb 23 at 15:43