Capacitor Inductance: Unraveling the Mystery

[sam986]

Can't find an answer to my question. Why do capacitors are so special when it comes to purity, unlike resistors and inductors. I know the capacitor somehow impedes the inductance in the circuit, but how? I just began studying the ac theory, and it boggles my mind.

 

[Simon Bridge]

Welcome to PF;
The capacitor counters an inductance in series with it due to the relationship between changing electric and magnetic fields.
It is not a simple one, and the theory you are learning now is not the whole story.
You'll need to be a bit patient.

 

[sophiecentaur]

Can't find an answer to my question. Why do capacitors are so special when it comes to purity, unlike resistors and inductors. I know the capacitor somehow impedes the inductance in the circuit, but how? I just began studying the ac theory, and it boggles my mind.

All components have 'parasitics'. (Try Google on Electronic component parasitics) Indeed, inductors are plagued with self capacitance and many high value inductors will self resonate at low Radio Frequencies (all those coils sitting next to each other with associated capacitance). I think the reason that Capacitors come to mind is that your average circuit has many more capacitors than inductors ('wound components' are expensive to make and tend to be avoided where possible). Even metal film resistors are often made with helical grooves in them which gives them significant inductance at UHF and above. You can buy more expensive resistors that have a longitudinal slot to adjust resistance; much better at high frequencies. Small, chip resistors and capacitors behave pretty well on circuit boards that operate well into the GHz region (look inside your computer).

 

[sam986]

Alright then thank you for the answers.

 

[alphy]

I can understand your confusion and fascination with capacitors and their role in circuits. Capacitors are indeed special in their ability to store and release electrical energy, and their unique characteristics make them crucial components in many electronic devices.

One of the reasons why capacitors are so special is because of their ability to store electric charge. This is due to the presence of two conductive plates separated by an insulating material, known as the dielectric. When a voltage is applied across the plates, one plate becomes positively charged and the other becomes negatively charged, creating an electric field between them. This separation of charge allows the capacitor to store energy in the form of an electric field.

Now, to address your question about the role of capacitors in reducing inductance in a circuit, it is important to understand the concept of reactance. Reactance is the measure of opposition to the flow of alternating current (AC) in a circuit, and it is caused by the presence of inductance or capacitance. In a pure inductor, the reactance is purely inductive, meaning it opposes changes in the current flow. However, in a pure capacitor, the reactance is purely capacitive and it opposes changes in voltage.

When a capacitor is added to a circuit, it creates a capacitive reactance that is opposite to the inductive reactance of the inductor. This results in a canceling effect, known as impedance, which reduces the overall inductance in the circuit. This is why capacitors are often used in circuits to reduce or eliminate unwanted inductance, which can cause issues such as voltage spikes and interference.

In summary, capacitors are special because they have the ability to store and release electrical energy and their presence in a circuit can help reduce inductance and improve circuit performance. I hope this explanation helps unravel the mystery of capacitors for you. Keep studying and exploring the world of AC theory, and you will soon understand and appreciate the unique properties of capacitors.