RFCapacitor vs Inductor: Key Differences Explained
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This article explores the differences between capacitors and inductors, two fundamental electronic components.
Capacitor
A capacitor is an electronic component designed to store electrical charge. In its simplest form, it consists of two parallel metal plates separated by an insulator, known as a dielectric.
Crucially, a capacitor does not allow direct current (DC) to flow through it, but it does allow alternating current (AC) to pass.
Figure 1: Various capacitor symbols (fixed, variable, and polarized).
Polarized capacitors require proper connection: current must enter through the positive terminal. Non-polarized capacitors can be connected either way around.
Capacitor Basics
Capacitance is measured in Farads (F), but in practice, you’ll often encounter units like µF (microfarads), nF (nanofarads), and pF (picofarads). Typical capacitance values range from 1pF to around 150,000 µF.
When choosing a capacitor for a specific application, you’ll need to consider its value, tolerance, and stability.
Inductor
In its simplest form, an inductor is a coil of wire, often wound around a core. This core can be air or a magnetic material like iron. An inductor with a magnetic core exhibits a significantly higher inductance compared to an air-cored inductor. The more turns in the coil, the greater the inductance.
Inductors oppose changes in current and possess inductance, denoted by “L”.
Inductance is measured in henries (H), millihenries (mH), and microhenries (µH).
Inductor Basics
Difference between Capacitor and Inductor
The following table summarizes the key differences between capacitors and inductors:
| Feature | Capacitor | Inductor |
|---|---|---|
| DC Current | Blocks direct current | Passes direct current |
| AC Current | Passes alternating current | Blocks alternating current |
| Voltage Change | Voltage cannot change instantly | Current cannot change instantly |
| Rapid Change Effects | Quick voltage change generates large current | Quick current change generates large voltage |
| Energy Storage | Stores energy in an electric field (E) | Stores energy in a magnetic field (H) |
| Frequency Behavior | Conducts best at high frequencies | Conducts best at low frequencies |
| Unit of Measurement | Farads | Henries |
| Major Types | Ceramic, electrolytic, tantalum | Multilayer, ceramic core, coupled |
| Voltage/Current Phase | Voltage lags behind current | Current lags behind voltage |
| Reactance | Capacitive reactance (XC) = 1/(2πfC) | Inductive reactance (XL) = 2πfL |
| Series Combination | (1/C) = (1/C1) + (1/C2) + … + (1/Cn) | L = L1 + L2 + … + Ln (Assuming no mutual inductance) |
| Parallel Combination | C = C1 + C2 + … + Cn | (1/L) = (1/L1) + (1/L2) + … + (1/Ln) (Assuming no mutual inductance) |
