Basic circuit element A to Z
If you have a little enthusiasm about electronics, you have often heard about resistors, capacitors, diodes, etc. But did you ever think about their classification, function, symbol and use? Here we discussed in a detailed manner about these basic circuit elements.
An electrical circuit is defined as a complete path for electrical current flow. These electric circuits consisting of resistors, capacitors, inductors, vacuum tube devices, voltage and current sources.
Each circuit component such as a resistor, capacitor, inductor, diode etc. is called basic circuit elements.
This classification is based on the number of terminals they have to connect with other components.
These elements have only two terminals to connect with other elements. Resistors, capacitors, diodes etc are the example of one port element.
These elements have more than two terminals to connect with other elements. Transformers have six terminals so it is a multiport element. Two-port elements having four terminals are the most common multiple port element.
Diode, transistor etc can amplify/rectify the ac power. Thus they are called active elements.
As the current-voltage relationship is not linear in case of a diode and transistor, they are also called non-linear elements. Ohm’s law and Kirchhoff’s law do not apply to the circuits consisting of non-linear elements.
Resistors, Capacitors and Inductors can not amplify or rectify ac power. Thus, they are called passive elements.
As the current-voltage relationship is linear in case of resistor, capacitor and inductor, they are also called linear elements. Ohm’s law and Kirchhoff’s law apply to the circuits consisting of linear elements.
Resistors are the most commonly used circuit elements. As the name suggests resistors generally resist the current flow through a circuit.
Resistor is a linear element meaning its current is linearly increasing or decreasing with the increase or decrease of voltage. Current-voltage relation defined as-f(V, I) =0
Resistors follow Ohm’s law,
V=i×R; where ‘V’ is the potential difference, ‘i’ is the current through the circuit, and ‘R’ is the resistance.
Power as a function of resistance: Power,
The SI unit of resistance is ‘Ohm‘
symbol: ‘Ω’
Dimension: Kg.m2.s-3.A-2
Colour-code is a standard way to define the resistance of a resistor only by seeing the colour bands on its body.
A capacitor is used to store the electric charge and release it when desired. Different types of capacitors are used in electric circuits.
A capacitor offers very high impedance to dc but very low impedance to ac. Capacitors used in this way are called blocking capacitors.
Another way to use a capacitor is the bypass capacitor. Here a capacitor is connected parallelly to a large resistance. It bypasses the ac that flows through the resistor.
The capacitors are named according to the use of dielectric inside it. There are various types of capacitors like plastic, polystyrene, paper, mica, ceramic and electrolytic capacitors.
Capacitors are always manufactured and used considering the polarity. They always have ‘+’ and ‘-‘ signs on them. A small fresh capacitor has come to the market with a longer wire in the positive side than the other side. Capacitors are connected with circuit boards or with other components very carefully otherwise it can be fatal.
For a capacitor current-voltage relationship is given by,
f(V, Q)=0
Meaning, current= capacitance×time rate of change of potential difference.
The SI unit of capacitance is ‘farad’.
Symbol: ‘F’
Dimension: s4.A2.m-2.kg-1
Inductors are basically coils of wire that can produce an induced voltage in it when the current through it varies with time.
For an inductor current-voltage relationship is given by,
f(Φ,i)=0
The SI unit of Inductance is ‘Henry‘.
Symbol: ‘H’
Dimension: ML2T-2I-2
Inductors, that have a large value of inductance are called choke coil.
Diode is an active, non-linear device also comes under the Basic Circuit Elements. The device is called “diode” as it has two (‘di’) electrodes. We often call it ‘Diode valve’ in an analogy that current always flows through it in one direction.
For further information about diode and other vacuum tubes please read our separate post on ‘vacuum tubes‘.
Transistor is also an active, non-linear element. It is a semiconductor device that uses either to amplify or switch the electrical signal.
There are different types of transistors like BJT, MOSFET, FET, NPN OR PNP etc according to their structure, polarisation, semiconductor material, application etc.
If you have any query regarding “Basic Circuit Eelments” please comment below. We will try our best to answer. Thank you.
Each circuit component such as a resistor, capacitor, inductor, diode etc. is called basic circuit element.
Diode, transistor etc can amplify/rectify the ac power. Thus they are called active elements.
Resistors, Capacitors and Inductors can not amplify or rectify ac power. Thus, they are called passive elements.
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