Capacitor vs Inductor: How Do Their Properties and Applications Compare?
The topic Difference Between Capacitor And Inductor is crucial for exams as it helps students understand the distinct roles and properties of these two fundamental passive components in electrical and electronic circuits. Comparing their functions aids problem-solving and conceptual clarity in Physics and Engineering exams.
Definition of Capacitor
A capacitor is a passive electronic component that stores electrical energy in the form of an electric field between its two plates separated by a dielectric material such as air or plastic. Its primary function is to oppose changes in voltage across its terminals.
The ability of a capacitor to store charge per unit voltage is called capacitance, measured in Farads (F). The formula for a capacitor is $Q = CV$, where Q is charge, C is capacitance, and V is voltage. For more details, refer to Inductive Reactance And Capacitive Reactance.
Definition of Inductor
An inductor is a passive component made from a coil of conducting wire that stores energy in the form of a magnetic field when current flows through it. It opposes any change in the current passing through its windings.
Inductance is the property that quantifies an inductor's ability to resist changes in current and is measured in Henry (H). The formula for inductance is $L = \frac{\phi}{i}$, where $\phi$ is magnetic flux, and $i$ is current. Practical understanding is linked to Inductive Reactance And Capacitive Reactance.
Difference Table
| Capacitor | Inductor |
|---|---|
| Stores energy as an electric field | Stores energy as a magnetic field |
| Opposes changes in voltage | Opposes changes in current |
| Composed of two plates with dielectric | Made of coiled conducting wire |
| Capacitance measured in Farads (F) | Inductance measured in Henry (H) |
| Symbol: Two parallel lines | Symbol: Coil or series of loops |
| Current leads applied voltage in AC | Current lags applied voltage in AC |
| Acts as open circuit for DC after charging | Acts as short circuit for DC in steady state |
| Blocks low-frequency signals | Blocks high-frequency signals |
| Used for filtering and smoothing signals | Used for chokes and tuning circuits |
| Energy stored: $E = \frac{1}{2}CV^2$ | Energy stored: $E = \frac{1}{2}LI^2$ |
| Dielectric determines its properties | Core material affects inductance |
| High efficiency at high frequencies | Efficient at low or power line frequencies |
| Application in timing circuits | Application in transformers and motors |
| Reactance decreases with frequency | Reactance increases with frequency |
| Charge storage is temporary | Maintains current flow, delays change |
| Does not allow steady DC to pass | Allows steady DC to pass |
| Initial current is zero at switch on | Initial voltage is zero at switch on |
| Used for power factor improvement | Used for power factor correction |
| Mainly resists sudden voltage changes | Mainly resists sudden current changes |
| Example: Ceramic, electrolytic capacitors | Example: Air core, iron core inductors |
Key Differences
- Capacitor stores electric energy, inductor stores magnetic energy
- Capacitor resists voltage change, inductor resists current change
- Capacitance measured in Farads, inductance in Henry
- Reactance of capacitor decreases with frequency, inductor increases
- Capacitor uses dielectric, inductor uses core material
Examples
A capacitor in a fan regulator adjusts the speed by controlling the voltage. An inductor in a tube light ballast limits the current flow to protect the lamp. Capacitors and inductors are frequently tested in circuit problems for entrance exams like JEE and NEET.
Application circuits such as Difference Between Current And Voltage discussions often use capacitors and inductors as illustrative examples.
Applications
- Capacitors used in filter and timing circuits
- Inductors used in transformers and power supplies
- Capacitors stabilize voltage in power systems
- Inductors block AC but pass DC in circuits
- Both applied in tuning resonant circuits
One-Line Summary
In simple words, a capacitor opposes changes in voltage and stores energy as an electric field, whereas an inductor opposes changes in current and stores energy as a magnetic field.
FAQs on What Are the Differences Between a Capacitor and an Inductor?
1. What is the difference between a capacitor and an inductor?
Capacitors and inductors are both passive electrical components but differ in the way they store and release energy.
Key differences:
- Capacitor stores energy in the form of an electric field between its plates.
- Inductor stores energy in the form of a magnetic field in its coil.
- Capacitors oppose changes in voltage, while inductors oppose changes in current.
- Unit of capacitance is the farad (F); unit of inductance is the henry (H).
2. How does a capacitor work?
A capacitor stores electrical energy by accumulating charge on its plates whenever a voltage is applied across it.
- It consists of two conductive plates separated by an insulating material (dielectric).
- When voltage is applied, one plate accumulates positive charge and the other negative.
- The stored energy can be released when needed, making capacitors useful in filtering, timing, and energy storage.
3. How does an inductor work?
An inductor stores energy in a magnetic field produced by the flow of current through a coil of wire.
- When current flows through the coil, it creates a magnetic field around it.
- The inductor resists sudden changes in current, making it useful for smoothing currents and filtering signals.
- The energy stored is proportional to the square of the current and the inductance value.
4. What are the main uses of capacitors?
Capacitors are widely used in electronic and electrical circuits for several key purposes.
- Energy storage in power supplies and flash units
- Filtering in power supplies to smoothen voltage fluctuations
- Coupling and decoupling in signal processing circuits
- Tuning circuits in radios and other devices
5. What are the main uses of inductors?
Inductors are electrical components that store energy as a magnetic field and are found in various applications.
- Filtering signals in electronic circuits
- Chokes to block high-frequency AC while allowing DC to pass
- Tuning circuits for specific frequencies in radios and transmitters
- Transformers for voltage conversions in power supplies
6. What are the differences between how capacitors and inductors behave in AC and DC circuits?
Capacitors and inductors exhibit different behaviors in AC and DC circuits.
- In a DC circuit: A capacitor acts as an open circuit after charging, while an inductor acts as a short circuit after steady-state is reached.
- In an AC circuit: A capacitor passes high-frequency signals easily and blocks low-frequency signals, while an inductor allows low-frequency signals and blocks high-frequency signals.
7. How do the units of capacitors and inductors differ?
Capacitors and inductors are measured using different standard units.
- Capacitance is measured in farads (F).
- Inductance is measured in henrys (H).
8. Can a capacitor and an inductor be connected together? What happens?
A capacitor and an inductor can be connected together in what is called an LC circuit.
- An LC circuit exhibits oscillatory behavior, where energy transfers back and forth between the capacitor and the inductor.
- This is the basis for radio tuning circuits, oscillators, and filters.
- At a certain resonant frequency, the circuit can store and exchange maximum energy between the electric and magnetic fields.
9. What is the main function of a capacitor in an electrical circuit?
The main function of a capacitor is to store and release electrical energy as needed in the circuit.
- It smoothens voltage variations.
- Filters out noise and stabilizes power supply.
- Enables signal coupling between circuit stages.
10. What is the main function of an inductor in an electrical circuit?
The primary function of an inductor is to oppose changes in current and store energy in a magnetic field.
- It filters out AC variations while passing DC.
- Stores and releases energy for use in oscillators and switching power supplies.
- Allows tunable circuits in radios and transmitters.
11. Why does a capacitor block DC but pass AC, while an inductor does the opposite?
A capacitor blocks direct current (DC) but allows alternating current (AC), whereas an inductor resists AC and allows DC to pass.
- Capacitor: Once charged by DC, it acts as an open circuit to DC, but for AC, it continuously charges and discharges, allowing AC to pass.
- Inductor: It offers minimum resistance to steady DC after an initial surge, but opposes changes caused by AC, thus impeding AC flow.
