Electronics & Software – Tips & Guide


Does direct current pass through the capacitor?

if a capacitor is initially not charged and someone uses the voltage as it is, induction will cause the capacitor to fill to the level of the applied voltage, therefore induction is not possible and no further charging will occur. this is well known and the period in which the filling (or use) occurs is referred to as the temporary period in which induction is present.

It is true that the capacitor will block dc, because induction is possible, but not when there is an electric potential difference between it and the dc source applied which results in induction. the only reason dc blocking capacitors are that when they are fully charged the voltage matches the supply voltage and no induction. this is not like ac where the given voltage changes constantly causing the capacitor to do the same thing as induction is always there. also one can see dc as ac at zero frequency.

Capacitors are made of materials that can be polarized and are therefore able to produce very high electrical flux densities in the material when subject to induction when turned on by electricity which is applied externally. field. this is known as dielectric material, which is used in making capacitors and is also known as a very good insulator; the air becomes a dielectric like that.

Because capacitors contain dielectric material which is an insulator, there is no way the current flows through them. However, when the dielectric material is subject to an external electric field (whether the axles or axles) it induces internal electrical flux density through the polarization of the dielectric material. during the transient period mentioned above, such polarization creates an internal voltage (or electric field) that is opposite to the dc voltage applied and once fully charged it matches the applied voltage so that no further current or charge flow in the material occurs.

This is no different from a transformer where the magnetic field applied from winding primarily induces or excites internal magnetic flux in the core of ferromagnetic material which gives the appearance of current flowing through the transformer core but not so.

in fact there is an energy transfer that occurs between a dc voltage source and a capacitor through an electromagnetic field where energy from the source is transferred and through polarization stored in the electric field of the dielectric material of the capacitor through the induction process during the transient period. therefore we only use induction to exploit the electrical properties of the dielectric material.

it is interesting that this question always appears with capacitors but never with transformers even though these phenomena are two things that are certain to each other. for this reason the mathematical concepts of displacement flows are developed to allow or explain for continuity and charge conservation in continuity equations because energy transfers through the em field through the induction process. capacitors that are filled analogously with a permanent magnet filled; the only difference is that in the previous energy it is stored in the electric field and in the latter in the magnetic field.

for laymen though it seems that the current flows through the capacitor which is why many people are surprised when they touch large terminal capacitors when they are not even connected to any supply source. in order to be safe all large capacitors must have resistors placed in their terminals or they must be short-circuited to prevent charging because of the electric field applied to it.

It depends on what you mean by the dc block. of course when the capacitor fills in, the inflow is in one terminal and exits from the other terminal until the capacitor has been charged to the given voltage. behaves as if a current is passing through but no electrons enter one terminal out of another terminal, so that in that sense it blocks the current.a better way to think about dc blocking is to imagine a voltage source that has ac and dc components, connected in series with capacitors and resistors. the capacitor will charge until the average voltage is equal to the dc component and this charging current will pass through the resistor until charging is complete. since then, the current in the resistor will match only the ac component of the voltage source and the dc component will cross the capacitor. in that sense, the dc component has been blocked from the load resistor.

if the dc component changes the input voltage, the capacitor will charge or release additional until the average voltage is equal to the average voltage applied and this transient current will flow in the resistor and appear on it as a transient voltage. in that sense, dc is not blocked.

It should be noted that, because a capacitor in a circuit with a resistor cannot charge instantly, the voltage on the capacitor cannot change instantly. that means that in this example, if the step change is made in the dc component of the input voltage, the voltage step will appear instantly in the load resistor, gradually dying when the capacitor fills over time to the new average dc voltage. in that case, the capacitor does not block the dc voltage change at first but only over time. You go into the question what you call a dc voltage because the change in step in the dc component of the input voltage is not really dc, it is really temporary.

For an electrical engineer, the term transient is understood as a moment of sudden change in electric current like when you turn on a light switch. now to answer your question, if you apply a single positive pulse to the capacitor the capacitor will receive the charge but as soon as the pulse drops, the capacitor will release it when it is in a circuit with another component such as a resistor (if by itself, it will only store charge). it will look like a capacitor makes the electrons pass through it but what really happens is it releases the same amount of charge.

it will look like a spring that when you compress and release, it will rise again. the other side of the capacitor is -, and that is why the capacitor has a phase phase 90 deg with voltage. no. direct current is blocked by the ideal capacitor. note that in the real world there is a small amount of leakage. also the real capacitor has a limited number of obstacles and inductances, but this is designed to be as small as practical. (some order of magnitude is smaller than capacitance.)

note that when alternating current is passed through a capacitor, the voltage is slightly attenuated based on the capacitance ratio of the capacitor to the remaining circuit resistance and frequency . AC current.