Circuit Elements - Active Passive Elements of Electrical Circuit
Circuit elements are those components of an electric circuit or electronic circuit which either can supply energy to the circuit or can take energy from the circuit. All the components of an circuit are connected together in required manner by conductors to form a desired and complete circuit. If the connecting conductor are taken as ideal, all the parts of the circuit, except the connecting conductors are circuit elements.
Types of Electric Circuit Elements
The electrical circuit elements
either absorb energy from circuit or deliver energy to the circuit. Based on that there are two types of electric circuit elements
, namely passive circuit elements
and active circuit elements
The circuit elements that receive energy (or absorb energy) and either convert it into heat or store it in an electric field
or a magnetic field
are called passive circuit elements
is taken as passive element since it can dissipate energy as heat as long as current flows through it but in any situation a resistor
cannot deliver energy to the circuit.
is also considered as passive element of circuit, because it can store energy in it as magnetic field, and can deliver it to the circuit, but not in continuous basis. The energy absorbing and delivering capacity of an inductor are limited and transient in nature. That is why, an inductor is taken as passive element of a circuit.
For same reason, a capacitor
is considered as passive element, because it can store energy in it as electric field
and deliver it to the circuit, but not in continuous basis. The energy dealing capacity of a capacitor is limited and transient too.
Active Circuit Element
The circuit elements which supply energy to the circuit are called active circuit element
Include voltage sources
, current sources
, and generators such as alternators
, dc generators
A voltage source
can be considered as an active element. If current
leaves from the positive terminal of the voltage source, the energy is delivered from the source to the circuit.
As per definition of active element of electrical circuit
, a battery
can be considered as active element, as it continuously delivers energy to the circuit during discharging.
A current source
is also considered as active element. The current supplied to the circuit by an ideal current source is independent of circuit voltage.
is an active circuit element, because, it can amplify the power of a signal. On the other hand, transformer
is not an active circuit element because it does not amplify power and the power remains same both in primary and secondary side. Although, a transistor
is an example of active circuit elements, but the transformer
is an example of passive circuit elements
The circuit elements can also be categorised as bilateral and unilateral.
Bilateral Circuit Element
Conduction of current in both directions in a circuit element with same magnitude is termed as bilateral circuit element
. It offers same resistance to the current of either directions.
This figure shows a bilateral circuit element can conduct from both sides and offers same resistance
for current from either side.
Unilateral Circuit Element
Conduction of current in one direction is termed as unilateral circuit element
. It does not offer same resistance to the current of either direction. The resistance of the unilateral circuit element
is different for forward current than that of reverse current.
This figure shows, a diode as unilateral circuit element. When diode
is forward biased it offers very small resistance
and conducts. While it is reverse biased, it offers very high resistance
and doesn't conduct. The circuit element can be categorized in another manner, such as lumped and distributed circuit elements
Lumped Circuit Elements
When the voltage
across and current through the element don't vary with dimension of the element, it is called lumped circuit elements
Resistor connected in any electrical circuit.
Distributed Circuit Element
When the voltage
across and current through the element change with dimensions of the element, it is called distributed circuit element
Resistance of the transmission line. It varies with the length of the line.
Electrical Circuit Symbol
An electric circuit
contains the symbol for every component and product. A circuit diagram uses symbols to represent parts of the circuit. Electrical circuit is designed and managed by using different software like ORCAD, CAD, MATLAB, SCADA. If you want to read any circuit you should familiar with the entire electrical circuit symbol