# A Brief Introduction On Resistance, Inductance, and Capacitance ## 1. Resistance

When current flows through a conductor, the conductor’s internal resistance property to hinder the current flow is called resistance. The components that play a blocking role in the circuit are resistors or resistors for short. The primary purpose of the resistor is to step down, divide or divide the current, and it is used as load, feedback, coupling, isolation, etc., in some special circuits.

The symbol of the resistor in the circuit diagram is the letter R. The standard resistance unit is ohms, denoted by R. Commonly used are kiloohm KΩ and megohm MΩ.

IKΩ=1000Ω 1MΩ=1000KΩ

## 2. Inductance

Like capacitors, inductors are also energy storage components. Inductors are generally made of coils. When AC voltage is applied to both ends of the coil, an induced electromotive force is generated in the coil, which prevents the current passing through the coil from changing. This resistance is called inductive reactance. The inductive reactance is proportional to the signal’s inductance and frequency. It has no blocking effect on direct current (regardless of the direct current resistance of the coil). Therefore, the functions of inductors in electronic Circuits are blocking, voltage transformation, coupling, and cooperation with capacitors for tuning, filtering, frequency selection, and frequency division.

The code name of the inductor in the circuit is L. The unit of inductance is Henry (denoted as H), and the commonly used ones are millihenry (mH) and microhenry (μH).

1H=1000mH 1mH=1000μH

Inductors are typical components of electromagnetic induction and conversion; the most common application is transformers.

## 3. Capacitance

Capacitors are also one of the most common components in electronic circuits. It is a component that stores electrical energy. The capacitor is composed of two conductors of the same size and quality, with a layer of insulating medium sandwiched between them. A charge is stored on the capacitor when a voltage is applied across it. Once there is no voltage, as long as there is a closed-loop, it will rerelease electricity. Capacitors prevent DC from passing through the circuit and allow AC to pass. The higher the frequency of the AC, the stronger the ability to pass. Therefore, circuits are commonly used for coupling, bypass filtering, feedback, timing, and oscillation.

The letter code for capacitors is C. The unit of capacitance is the farad (denoted as F), and μF (microfarad) and PF (i.e., μμF, picofarad) are commonly used.

1F=1000000μF 1μF=1000000PF

The behavior of capacitors in circuits is nonlinear. The resistance to current flow is called capacitive reactance. Capacitive reactance is inversely proportional to capacitance and the frequency of the signal.