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The difference between Capacitor and Inductor is explained on the basis of various factors such as the calculation of stored energy, the flow of current, their behavior in both AC and DC circuits. Capacitors and Inductors are two vital electrical components that are used in multiple electrical devices. A capacitor is used for opposing any kind of change that occurs in the voltage. An inductor, on the other hand, is used to oppose a change in the current. The basic difference between a capacitor and an inductor is that a capacitor resists change in voltage while the inductor resists the change in current. The capacitors store the energy in the form of an electric field while the inductor stores energy in the form of a magnetic field.
| Table of Content |
Key Takeaways: Capacitor, Inductor, Electrical Devices, Electrical Circuit, Frequencies, Inductance, Capacitance, Signal, Transmission Systems
Difference between Capacitor and Inductor
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The various Capacitor vs Inductor differences are as tabulated below:
| Capacitor | Inductor |
|---|---|
| A capacitor refers to a device that mainly resists any type of change in voltage. | An inductor is a device that resists any kind of change in the amount of current passing through. |
| The energy is stored in a capacitor in the form of an electric field. | In an inductor, the energy is stored in the magnetic field. |
| A capacitor does not conduct current. | An inductor is a device that does conduct current. |
| A capacitor behaves as a short circuit only when an Alternating Current (AC) is applied. | An inductor behaves as a short circuit only when a Direct Current (DC) is applied. |
| A capacitor is highly efficient when high frequencies are applied. | An inductor works with high efficiency with low frequencies. |
| The voltage lags the current by π/2. | The current lags the voltage by π/2. |
| For a DC circuit, the capacitor acts as an insulator. | For a DC circuit, the inductor acts as a conductor. |
| The energy is stored in a capacitor in terms of the voltage i.e. ½ CV2. | The energy is stored in an inductor in terms of the current i.e. ½ LI2. |
| The unit used to measure the capacitance of a capacitor is Farads, also denoted as F. | The unit used to measure the inductance of an inductor is Henry, also denoted as H. |
| A capacitor with large capacitance is used in power supplies with high voltage. | An inductor is used when the resonance is present when specific important frequencies are applied. |
| Some types of capacitors are electrolytic, tantalum, and ceramic capacitors. | Some types of inductors are multilayer inductors, Coupled inductors, ceramic core inductors, and molded inductors. |
- Both capacitors and inductors are electrical components that have different functions and different work processes.
- When we use a capacitor and an inductor together in an electrical circuit, the resistance of the circuit changes to zero.
- When current is passed through the circuit, the current goes up to infinity, and hence the electrical potential of the inductor changes.
- The process is repeated infinite times because of the absence of resistance.
- When both capacitor and inductor are used together, they create a filter for the analog circuits, they are also used in LC circuits where the circuits act as a resonator.
- These circuits are then used in surveillance systems, amplifiers, mixers, oscillators, etc.
- They are used in order to produce signals only at specific frequencies.
- Hence, capacitors and inductors, both individually and when combined together, are of great use in electrical circuits.
Also Read:
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|---|---|---|
| AC Voltage Applied to a Resistor | Power Factor | Types of AC Motors |
| Capacitive Reactance Formula | Transformer Formula | Power in AC Circuit |
What is Capacitor?
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A capacitor is a two-terminal device that is used to resist any change in the voltage. A capacitor is used to store electrical energy in a given electrical field.
- The capacitor produces an effect known as capacitance.
- It is usually measured in Farads, which is represented by F.
- A capacitor is highly efficient at high frequencies.
- A capacitor is formed of two or more plates that are placed in a parallel manner with a little gap that exists between the conductive plates.
- The conductive plates are separated from each other via air or another insulating material.
- The insulating layer that exists between any two plates is referred to as the Dielectric.
Due to the presence of an insulating layer in between, a capacitor is not able to conduct current. For a DC, it behaves as an insulator while for AC, it behaves as a short circuit. Various types of capacitors that are commonly used are tantalum capacitors, ceramic capacitors, and electrolytic capacitors.
Capacitor
Uses of Capacitors
Capacitors are mainly used for a variety of applications. Some of them are:
- They are mainly used in High voltage supplies.
- Capacitors are used for the storage of energy.
- Capacitors are used in order to maintain power when the batteries are being charged.
- Capacitors have applications in circuits dependent on time.
- They are used for the conversion of AC into DC.
- Capacitors are used as sensors.
- They have applications in flash circuits of cameras and also in tuning circuits.
What is an Inductor?
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An inductor is a two-terminal electrical component that resists any change in the current. Inductors are responsible for storing energy in a form of a magnetic field.
- An inductor can also be called a reactor or a choke.
- The inductor produces an effect referred to as the inductance. Inductance is measured in Henry, denoted by H.
- The inductor can be formed by wounding an insulated wire over a core material.
- It is designed in this way that whenever current flows through it, a magnetic field is produced in the core or in itself.
- When low frequencies are applied, an inductor works in its best capacity.
- When some important frequencies are applied while the resonance is present, an inductor is highly efficient.
- The inductor conducts current through itself.
- It usually conducts alternating current, AC but when a direct current, DC is applied, it starts behaving like a short circuit.
The various types of inductors that are in use are ceramic core inductors, coupled inductors, multilayer inductors, and molded inductors. When two inductors join together, they form a transformer.
Inductor
Uses of Inductor
The various applications of the inductor are:
- Inductors are used to filter the current in the form of analog signals.
- They prevent radio frequency interference.
- They are used as energy storage units in various power supplies.
- Inductors find application in electrical transmission systems.
Also Read:
| Related Articles | ||
|---|---|---|
| Alternating Current Important Questions | LC Oscillations | Transformers |
| AC Voltage Applied to an Inductor | AC Voltage Applied to a Capacitor | AC Voltage Applied to a Series LCR Circuit |
Things to Remember
- The capacitor can be understood as a two-terminal device that is used to resist any change in the voltage.
- The difference between capacitor and inductor is that the capacitor resists any change in voltage while the inductor resists any change in the current.
- A capacitor is formed of two or more plates that are placed in a parallel manner with a little gap that exists between the conductive plates.
- The inductor is designed in a way that whenever current flows through it, a magnetic field is produced in the core or in itself.
- Capacitors are used in order to maintain power when the batteries are being charged.
- Inductors are used to filter the current in the form of analog signals.
- The energy in an inductor is stored in the form of a magnetic field while the capacitor stores the energy in the form of an electric field.
Previous Year Questions
- The mean or average value of AC over a complete cycle is… [COMEDK UGET 2015]
- Formation of Eddy currents has desirable effects in 1. Electromagnetic damping… [COMEDK UGET 2008]
- As resistance in a series resonant circuit increases (i) sharpness of resonance… [COMEDK UGET 2010]
- An inductor coil when connected to a 12V battery draws a steady current of 6A… [COMEDK UGET 2010]
- A step up transformer has turns ratio 10:1. A source of emf 2 volts is fed to the… [COMEDK UGET 2005]
- Resonance frequency of L-C-R series AC circuit is f0… [GUJCET 2007]
- In transformer, core is made of soft iron to reduce… [UPSEE 2010]
- For a series LCR circuit, the phase difference between current and voltage… [BCECE 2003]
- Alternating current is transmitted to take places… [JCECE 2007]
- A choke is preferred to a resistance for limiting current in AC circuit because… [JCECE 2009]
- An LCR series circuit, connected to a source E is at resonance… [BCECE 2009]
- A coil of resistance R and inductance L is connected to a battery of emf E volt… [BCECE 2010]
- In an AC circuit, V and i are given by V = 100 sin (100t) volt and i = 100 sin… [BCECE 2010]
- In non-resonant circuit, what will be the nature of the circuit for frequencies… [BHU UET 2008]
- ln an AC circuit, the current lags behind the voltage by…
- An arc lamp requires a direct current of 10 A at 80V…
- A lamp consumes only 25% of the peak power in an ac circuit…
- The power dissipated in an AC circuit is zero if the circuit is… [KEAM]
- An LCR series circuit is at resonance. Then…
- A transformer is used to light a 100W and 110 V lamp...
Sample Questions
Ques. What is capacitance? List down some uses of a capacitor. (5 marks)
Ans. Capacitance refers to the ability of an electric circuit to store the electric energy in the form of an electrostatic field.
Capacitors have multiple applications. Some of them are as follows:
- They are used as filters in Alternating Current Circuits or AC Circuits.
- They are used for the correction of the power factor of an electrical system.
- They improve the torque in motors.
Ques. What is an inductor? In terms of physical parameters, on what factors does the inductance of an inductor depend? (5 marks)
Ans. An inductor is referred to a coil that is made up of an insulated wire wound with a fixed number of turns over an iron core. When the current flows through the coil, it stores energy in the form of a magnetic field. Inductors have a property known as inductance that opposes any change in the amount of current flowing through the coil. The unit of inductance is Henry, also denoted by H.
The inductance value of an inductor depends on the following factors:
- Permeability of the core, µ
- The number of turns, N
- The cross-sectional area of the core, a
- Length of a magnetic circuit, l
The inductance is directly proportional to the area of the core, the number of turns, and the permeability of the core, and is inversely proportional to the length of the given magnetic circuit.
Inductance, also denoted by L = N2aµ0µr/l
Ques. Describe the basic construction of a capacitor. (5 marks)
Ans. A basic capacitor is formed of two electrodes that are separated via a dielectric medium or material. The conductive plates or the electrodes are generally good conductors of electricity. Hence, electric current passes easily through them. However, the dielectric medium or material that is present in between these conductive plates is a poor conductor of electricity. Hence, the material does not allow an electric current to pass through it.
The electric charges that try to move from one conductive plate to another will eventually be trapped within the plate or the electrode due to the strong opposition that comes from the dielectric. Hence, we can say that the electric charge is built up of the electrodes.
Ques. What is the polarization of a dielectric medium? (5 marks)
Ans. When a dielectric is placed between two charged plates, the medium's polarisation produces an electric field that opposes the field of the charges that exist on the plate. Therefore, an externally applied electric field causes a dipole moment to arise in an insulating material, which is known as dielectric polarisation. When a current interacts with a dielectric (insulating) substance, the dielectric material shifts its charge distribution, with positive charges aligning with the electric field and negative charges aligning against the electric field. Important circuit parts like capacitors can be produced through this phenomenon.
Ques. Explain the concepts of self-inductance and mutual inductance. (5 marks)
Ans. Self Inductance
The inducing of an emf across a coil by varying the magnetic flux that is produced as the result of change of current in the coil itself is known as self-inductance.
The self-inductance, represented by e, can be calculated by the given formula:
Self-induced emf or e = L.dI/dt
dI/dt refers to the rate of change of current,
Therefore, the induced emf is directly proportional to the rate of change of current that is passing through the inductor.
Mutual Inductance
Mutual inductance is a varying magnetic flux that is created as a result of a change in the value of current in the coil that produces an emf in an adjacent coil which is placed inside the magnetic field.
Mutually induced emf in the second coil, denoted by e2 can be given by the following formula
e2 = M.dI1/dt
Here, M refers to a constant mutual inductance
dI1/dt refers to the rate of change of current in the 1st coil.
Ques. Explain the principle of a capacitor. (3 marks)
Ans. A capacitor can be defined as a small device that is used to store a very large amount of electric charge in a small room.
For instance, let us take an insulated metal plate A and charge it to its maximum potential. When we bring another insulated metal plate B near plate A, a negative charge will be produced near plate A and a similar amount of positive charge will be produced on another side of the metal plate B.
Ques. How do inductors act in the AC and DC circuits? Mention a few applications of the inductors. (5 marks)
Ans. The inductors in an AC circuit provide inductive reactance that is directly proportional to the frequency of the supply current.
Inductive reactance, XL = 2π x f x L
Inductors generally consist of a lagging power factor. The current lags by 90° in a purely inductive circuit.
In a DC circuit, however, when we apply a voltage across an inductor, an emf is induced across the coil that is opposite to the polarity of the applied voltage which is equal to L x dI/dt. At this instant, the flow of current will be at the minimum level and gradually it achieves the maximum value of current. Now, the current will approximately be equal to V/R. Now, as long as the current supply is constant dI/dt = 0, the amount of current supplied only depends on the resistance present in the circuit.
A few applications of inductors are as follows:
- A variety of power supply circuits such as transformers, SMPS circuits, and buck converters make use of inductors.
- They are also used in pi filters, L or choke filters, for the purpose of filtering the outputs of rectifiers.
- Inductors are also used in RF transceiver tuning circuits and AC filter circuits.
- They are also used in oscillator circuits or Tank circuits for AC generation.
Ques. Mention the main points of difference between capacitor and inductor. (5 marks)
Ans. The differences between capacitors and inductors are as given below:
- Capacitor is an electric device that is involved and used to oppose the abrupt changes in the voltage (dV/dt) while an inductor refers to an electrical device that opposes any change in the current (dl/dt) in an electrical circuit.
- In a capacitor, energy is stored in the form of an electric field while in an inductor, the energy is stored in the form of a magnetic field.
- Current does not flow through the plates of a capacitor while it does flow through the inductor plates.
- When a capacitor is added to a resistor in a series combination in a DC circuit, the current initially remains high but afterward, it falls to zero value. While, on the other hand, when an inductor is added to a resistor in a parallel combination, the current initially has lower values but later with time it constantly increases.
- The various types of capacitors are tantalum, mica, electrolyte, and ceramic capacitors while the various types of inductors are flip side inductors, coupled inductors, ceramic core, and multilayer inductors.
- The energy stored in a capacitor is calculated in terms of its voltage, i.e. ½ CV2 while the energy that is stored in an inductor is calculated in terms of the current that flows through it i.e. ½ LI2.
- A capacitor is used in power supplies to smooth out the output of a rectifier. Capacitors are used in electrical power systems for the correction of the power factor. On the other hand, inductors are extensively used in transformers, radio, TV, and it is also used as current limiter.
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