Differences between resistors, capacitors, and inductors
The three electronic components resistors, capacitors, and inductors are particularly important and are known as the “three major passive components.” These three passive components store, consume, and filter energy from the outside world, but do not supply or amplify energy.
Understanding how each component works and handles energy gives us greater insight into the operation and performance of the entire circuit.
This article summarizes the differences in their features and mechanisms.
The role and mechanism of resistors
A resistor is a component that controls and limits the flow of electric current. Based on Ohm’s law, the relationship between voltage (V) and current (I) is expressed by the following formula:
V=IR
*V represents voltage, I represents current, and R represents resistance.
The resistance value is determined by the material the resistor is made of (such as carbon or metal film) and its dimensions; the higher the resistance, the more it will restrict the flow of electrical current.
When current flows through a resistor, it consumes electrical energy as heat. This energy conversion is irreversible and electrical energy is released to the outside as heat, so resistors are considered components that consume electrical energy.
The main role of a resistor is to prevent overcurrent and distribute voltage within a particular circuit.
Resistor Utilization Series
Electric heater: Increases temperature by converting electric current into heat
LED lighting: Protecting LEDs by limiting current
Audio equipment: Controls the signal current and voltage, and adjusts the volume
The role and mechanism of capacitors
A capacitor is an electronic component that stores energy in the form of an electric field. Its simple structure consists of two conductive plates sandwiching an insulator (dielectric).
When a voltage is applied to a capacitor, a charge builds up between the plates. When the voltage is removed, the capacitor discharges the stored charge, returning energy to the circuit.
The energy stored in the electric field is mainly used in AC circuits, and is often used as a filter circuit to block DC. Capacitors are also used to smooth out power.
Examples of using capacitors
Camera flash: A large-capacity capacitor is used to temporarily store power, and the energy is released all at once when the shutter button is pressed, producing a strong light.
Smartphone battery circuit: Relieving sudden voltage fluctuations and maintaining a stable power supply
Audio Equipment: Reproducing clear audio signals with noise filters.
The role and mechanism of inductors
An inductor is a component that stores energy in a magnetic field. When a current flows through a conductor wound into a coil, a magnetic field is generated and energy is stored. When the current stops, the magnetic field collapses and the stored energy is returned to the circuit.
The energy storage function is used for energy transfer in power circuits and switching power supplies.
Inductors also have the property of resisting sudden changes in current. When the current changes, the magnetic field also changes, which creates a current in the opposite direction. This “self-induction” suppresses sudden changes in current and stabilizes the circuit.
Suppressing current changes helps eliminate noise and stabilize voltage in AC and power supply circuits.
Inductors are particularly suited to filtering high frequencies, offering resistance to signals while allowing low frequencies and direct current to pass, eliminating noise and stabilizing signals.
Examples of using inductors
Switching power supply: Suppresses fluctuations in current and voltage to provide stable power
Motor control: smooths current and removes noise, making motor operation smoother and more efficient.
Radio: When you turn the tuning dial on a radio receiver, the inductor changes the resonant frequency to tune to a particular radio station.
Difference Between Capacitor and Inductor
Both capacitors and inductors are passive components that store energy, but their use varies depending on the application of the circuit.
The characteristics of each are summarized below.
Capacitor Characteristics
● Storing energy in an “electric field”
● It operates in response to changes in “voltage” and stores and releases electric charge.
● It can store and release electric charge in a short time, making it suitable for rapid energy supply.
● Allows high frequencies to pass easily, but blocks low frequencies and direct current.
Inductor Characteristics
● Storing energy in a “magnetic field”
● It operates according to changes in “current” and resists fluctuations in current.
● Energy is stored and released relatively slowly, which makes the current change more gradual.
● Low frequencies and direct current pass easily, but high frequencies have difficulty passing through.
Due to these differences in characteristics, capacitors are used for voltage stabilization, high-frequency filtering, and temporary energy storage, while inductors are used for current smoothing and high-frequency filtering.