Page 1
Network Theory
Current: Electric current is the time rate of change of charge flow.
• Charge transferred between time t
o
and t
Sign Convention: A negative current of –5A flowing in one direction is same as a
current of +5A in opposite direction.
Voltage: Voltage or potential difference is the energy required to move a unit
charge through an element, measured in volts.
Power: It is time rate of expending or absorbing energy.
• Law of conservation of energy must be obeyed in any electric circuit.
• Algebraic sum of power in a circuit, at any instant of time, must be zero.
i.e. SP = 0
Circuit Elements:
Passive element: If it is not capable of delivering energy, then it is passive
element. Example: Resistor, Inductor, and Capacitor
Page 2
Network Theory
Current: Electric current is the time rate of change of charge flow.
• Charge transferred between time t
o
and t
Sign Convention: A negative current of –5A flowing in one direction is same as a
current of +5A in opposite direction.
Voltage: Voltage or potential difference is the energy required to move a unit
charge through an element, measured in volts.
Power: It is time rate of expending or absorbing energy.
• Law of conservation of energy must be obeyed in any electric circuit.
• Algebraic sum of power in a circuit, at any instant of time, must be zero.
i.e. SP = 0
Circuit Elements:
Passive element: If it is not capable of delivering energy, then it is passive
element. Example: Resistor, Inductor, and Capacitor
Active element: If an element is capable of delivering energy independently, then
it is called active element. Example: Voltage source, and Current source.
Linear and Non linear elements: If voltage and current across an element are
related to each other through a constant coefficient then the element is called as
linear element otherwise it is called as non-linear.
Unidirectional and Bidirectional: When elements characteristics are independent
of direction of current then element is called bi-directional element otherwise it is
called as unidirectional.
• R, L & C are bidirectional
• Diode is a unidirectional element.
• Voltage and current sources are also unidirectional elements.
• Every linear element should obey the bi-directional property but vice versa
as is not necessary.
Resistor: Linear and bilateral (conduct from both direction)
• In time domain V(t) = I(t)R
• In s domain: V(s) = RI(s)
• l = length of conductor, ?= resistivity, A = area of cross section
Page 3
Network Theory
Current: Electric current is the time rate of change of charge flow.
• Charge transferred between time t
o
and t
Sign Convention: A negative current of –5A flowing in one direction is same as a
current of +5A in opposite direction.
Voltage: Voltage or potential difference is the energy required to move a unit
charge through an element, measured in volts.
Power: It is time rate of expending or absorbing energy.
• Law of conservation of energy must be obeyed in any electric circuit.
• Algebraic sum of power in a circuit, at any instant of time, must be zero.
i.e. SP = 0
Circuit Elements:
Passive element: If it is not capable of delivering energy, then it is passive
element. Example: Resistor, Inductor, and Capacitor
Active element: If an element is capable of delivering energy independently, then
it is called active element. Example: Voltage source, and Current source.
Linear and Non linear elements: If voltage and current across an element are
related to each other through a constant coefficient then the element is called as
linear element otherwise it is called as non-linear.
Unidirectional and Bidirectional: When elements characteristics are independent
of direction of current then element is called bi-directional element otherwise it is
called as unidirectional.
• R, L & C are bidirectional
• Diode is a unidirectional element.
• Voltage and current sources are also unidirectional elements.
• Every linear element should obey the bi-directional property but vice versa
as is not necessary.
Resistor: Linear and bilateral (conduct from both direction)
• In time domain V(t) = I(t)R
• In s domain: V(s) = RI(s)
• l = length of conductor, ?= resistivity, A = area of cross section
• Extension of wire to n times results in increase in resistance:
• Compression of wire results in decrease in resistance:
Capacitor: All capacitors are linear and bilateral, except electrolytic capacitor
which is unilateral.
• Time Domain:
• In s-domain:
• Capacitor doesn’t allow sudden change of voltage, until impulse of
current is applied.
• It stores energy in the form of electric field and power dissipation in ideal
capacitor is zero.
Impedance:
Inductor: Linear and bilinear element
• Inductor doesn’t allowed sudden change of current, until impulse of
voltage is applied. It stores energy in the form of magnetic field.
• Power dissipation in ideal inductor is zero.
Page 4
Network Theory
Current: Electric current is the time rate of change of charge flow.
• Charge transferred between time t
o
and t
Sign Convention: A negative current of –5A flowing in one direction is same as a
current of +5A in opposite direction.
Voltage: Voltage or potential difference is the energy required to move a unit
charge through an element, measured in volts.
Power: It is time rate of expending or absorbing energy.
• Law of conservation of energy must be obeyed in any electric circuit.
• Algebraic sum of power in a circuit, at any instant of time, must be zero.
i.e. SP = 0
Circuit Elements:
Passive element: If it is not capable of delivering energy, then it is passive
element. Example: Resistor, Inductor, and Capacitor
Active element: If an element is capable of delivering energy independently, then
it is called active element. Example: Voltage source, and Current source.
Linear and Non linear elements: If voltage and current across an element are
related to each other through a constant coefficient then the element is called as
linear element otherwise it is called as non-linear.
Unidirectional and Bidirectional: When elements characteristics are independent
of direction of current then element is called bi-directional element otherwise it is
called as unidirectional.
• R, L & C are bidirectional
• Diode is a unidirectional element.
• Voltage and current sources are also unidirectional elements.
• Every linear element should obey the bi-directional property but vice versa
as is not necessary.
Resistor: Linear and bilateral (conduct from both direction)
• In time domain V(t) = I(t)R
• In s domain: V(s) = RI(s)
• l = length of conductor, ?= resistivity, A = area of cross section
• Extension of wire to n times results in increase in resistance:
• Compression of wire results in decrease in resistance:
Capacitor: All capacitors are linear and bilateral, except electrolytic capacitor
which is unilateral.
• Time Domain:
• In s-domain:
• Capacitor doesn’t allow sudden change of voltage, until impulse of
current is applied.
• It stores energy in the form of electric field and power dissipation in ideal
capacitor is zero.
Impedance:
Inductor: Linear and bilinear element
• Inductor doesn’t allowed sudden change of current, until impulse of
voltage is applied. It stores energy in the form of magnetic field.
• Power dissipation in ideal inductor is zero.
Page 5
Network Theory
Current: Electric current is the time rate of change of charge flow.
• Charge transferred between time t
o
and t
Sign Convention: A negative current of –5A flowing in one direction is same as a
current of +5A in opposite direction.
Voltage: Voltage or potential difference is the energy required to move a unit
charge through an element, measured in volts.
Power: It is time rate of expending or absorbing energy.
• Law of conservation of energy must be obeyed in any electric circuit.
• Algebraic sum of power in a circuit, at any instant of time, must be zero.
i.e. SP = 0
Circuit Elements:
Passive element: If it is not capable of delivering energy, then it is passive
element. Example: Resistor, Inductor, and Capacitor
Active element: If an element is capable of delivering energy independently, then
it is called active element. Example: Voltage source, and Current source.
Linear and Non linear elements: If voltage and current across an element are
related to each other through a constant coefficient then the element is called as
linear element otherwise it is called as non-linear.
Unidirectional and Bidirectional: When elements characteristics are independent
of direction of current then element is called bi-directional element otherwise it is
called as unidirectional.
• R, L & C are bidirectional
• Diode is a unidirectional element.
• Voltage and current sources are also unidirectional elements.
• Every linear element should obey the bi-directional property but vice versa
as is not necessary.
Resistor: Linear and bilateral (conduct from both direction)
• In time domain V(t) = I(t)R
• In s domain: V(s) = RI(s)
• l = length of conductor, ?= resistivity, A = area of cross section
• Extension of wire to n times results in increase in resistance:
• Compression of wire results in decrease in resistance:
Capacitor: All capacitors are linear and bilateral, except electrolytic capacitor
which is unilateral.
• Time Domain:
• In s-domain:
• Capacitor doesn’t allow sudden change of voltage, until impulse of
current is applied.
• It stores energy in the form of electric field and power dissipation in ideal
capacitor is zero.
Impedance:
Inductor: Linear and bilinear element
• Inductor doesn’t allowed sudden change of current, until impulse of
voltage is applied. It stores energy in the form of magnetic field.
• Power dissipation in ideal inductor is zero.
Mesh Analysis:
• Path - A set of element that may be traversed in order, without passing thru
the same node twice
• Loop - a closed path
• Mesh - A loop that does not contain any other loop within it
• Planar Circuit - A circuit that may be drawn on a plane surface in such a way
that there are no branch crossovers
• Non-Planar Circuit - A circuit that is not planar, i.e, some branch(es) pass
over some other branch(es) (Can not use Mesh Analysis)
Transformer: 4 terminal or 2-port devices.
• N
1 >
N
2
: Step down transformer
• N
2
> N
1
: Step up transformer
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