Ohms Law
Ohm’s
5. In a resistance, if the loop direction is
law
states
the
relationship
between electric current and potential
difference.
The
current
that
flows
through most conductors is directly
proportional to the voltage applied to it.
Georg Simon Ohm, a German physicist
was the first to verify Ohm’s law. V= IR
KIRCHHOFFS LAW
physicist,
negative resistance voltage drop.
Maxwells Mesh Equations
This method was first proposed by
Maxwell using the voltage law only. The
method involves a set of independent
loop currents assigned to as many
meshes as exist in the circuit, and these
Kirchhoff's Law was named after the
German
the same as the current direction,
Gustav
Robert
Kirchhoff (1824-1887)
currents are employed in connection
with appropriate resistances when the
Kirchhoff voltage law equations are
written. The arbitrarily assumed loop
1. Current Law (KCL)- the algebraic sum
currents may or may not exist in the
of the currents at any junction of an
various resistors but when determined
electric circuit is zero.
will readily yield the desired values by
2. Voltage Law (KVL) - the algebraic
sum of the emf's and the resistance
voltage drops in any closed loop of an
electric circuit is zero.
Sign Conventions for Kirchhoff's Laws:
1. Current towards the node, positive
current.
2.
Current
away
from
the
node,
negative current.
3. In a voltage source, if the loop enters
on minus and goes out on plus, positive
emf.
4. In a voltage source, if loop enters on
plus and goes out on minus, negative
emf.
simple
algebraic
additions.
The
scheme offers the advantage that
fewer equations need to be written to
solve a given problem.
Steps to determine mesh currents
1. Assign mesh currents to the meshes.
A mesh is a loop which does not contain
any other loops within it.
2. Apply KVL to each of the n meshes.
Use Ohm's law to express the voltages
in terms of the mesh currents.
3. Solve the resulting n simultaneous
equations to get the mesh currents.
Superposition Theorem
The Superposition Theorem states that
"the voltage across or current through
an element in a linear circuit is the
Network-defined
algebraic sum of the voltages across or
interconnection of components such as
currents through that element due to
resistors
each
complicated circuit.
independent
source
acting
alone". The idea of the theorem lies on
the linearity property. The independent
voltage sources are represented by
their internal resistance if given or
and
as
batteries
the
forming
a
Branch (b) - represents a single
element such as a voltage source or a
resistor.
simply with zero resistance, i.e., short
Ground- a point in a circuit as a
circuits if internal resistances are not
reference point. This reference point is
mentioned. The independent current
known as Ground (GND) and carries a
sources are represented by infinite
voltage of 0V. Voltage measurements
resistance,
are relative measurements.
i.e.,
open
circuits.
The
dependent sources are not sources but
dissipative components - hence they
are active at all the times. A dependent
source has zero value only when its
control voltage or current is zero. A
linear network is one whose parameters
are constant, i.e., they do not change
with voltage and current.
The
three
steps
to
Node (n) - the point of connection
between two or more branches. A node
is a point of intersection/connection
within a data communication network.
In an environment where all devices are
accessible through the network, these
devices are all considered nodes. The
individual
apply
the
definition
of
each
node
depends on the type of network it refers
Superposition Theorem.
to.
1. Turn off all independent sources
Junction- points where three or more
except one source. Find the output
wires connect. Label each junction with
(voltage or current) due to the active
the currents and directions into and out
source using conventional techniques
of it. Make sure at least one current
like Ohm's Law and voltage and current
points into the junction and at least one
division theorems.
current points out of the junction.
2. Repeat step for each of the other
Loop (l) - any closed path in a circuit.
independent sources.
3. Find the total contribution by adding
algebraically all contributions due to
the inde- pendent sources.
Mesh - a loop which does not contain
any other loops within it.
Characteristic of Real Current Source
Characteristic of Real Voltage Source
a real current source has a limited
a real voltage source has a limited
range of output current and may vary
range of output voltage and Real-
with
world sources of electrical energy, such
changes
in
the
load
or
temperature.
as batteries and generators,
Characteristic of Ideal Current Source
combination of an ideal voltage source
and
that generates a constant current that
of impedance elements.
load connected to it. This means that
be
modeled for analysis purposes as a
An ideal current source is a component
remains unchanged regardless of the
can
additional
combinations
Characteristic of Ideal Voltage Source
an ideal current source will provide a
an ideal voltage source produces a
consistent current output even if the
fixed voltage output that does not vary
load
with changes in the current flowing
resistance
changes. An
ideal
current source is an idealized concept
that does not exist in reality but serves
as a fundamental building block for
many electronic circuits.
through the circuit.
An ideal
voltage
source is
terminal
device
that
a
two-
maintains
a
fixed voltage drop across its terminals.
An ideal current source is primarily used
It is often used as a mathematical
in circuits where a constant current
abstraction that simplifies the analysis
output is required, regardless of the
of real electric circuits. If the voltage
load
includes
across an ideal voltage source can be
drivers,
specified independently of any other
resistance.
applications
such
This
as
LED
battery chargers, and motor controllers,
variable
among others.
an independent voltage source.
an ideal current source can be used to
Conversely, if the voltage across an
power multiple loads in parallel, and
ideal voltage source is determined by
each
some other voltage or current in a
load
will
receive
the
same
in
a
is
called
circuit,
must be taken to ensure that the total
a dependent or controlled
current output of the current source is
source. A mathematical model of an
sufficient
amplifier
power
simultaneously.
all
the
loads
will
is
it
constant current output. However, care
to
it
circuit,
include
called
voltage
dependent
voltage sources whose magnitude is
governed by some fixed relation to an
input signal, for example.[2] In the
analysis of faults on electrical power
systems,
the
whole
interconnected
network
sources
of
and
transmission lines can be usefully
replaced by an ideal (AC) voltage
source
and
a
single
equivalent
impedance.
The internal
resistance of
an
ideal
voltage source is zero; it is able to
supply or absorb any amount of
current. The current through an ideal
voltage
source
is
completely
determined by the external circuit.
When connected to an open circuit,
there is zero current and thus zero
power. When connected to a load
resistance, the current through the
source approaches infinity as the load
resistance approaches zero (a short
circuit). Thus, an ideal voltage source
can supply unlimited power.
Note: The primary limitation of using
ideal current and voltage sources in
real-world circuits is that they are
idealized concepts that do not exist in
reality. Real sources have limitations
such as finite output current and
voltage range, internal resistance, and
noise
that
can
affect
circuit
performance. Additionally, the cost of
implementing ideal sources in real
circuits
may
be
prohibitive,
and
compromises may need to be made to
achieve the desired performance.
Voltage Divider
A voltage divider is a fundamental
circuit in the field of electronics which
can produce a portion of its input
voltage as an output. It is formed using
two
resistors
(or
any
passive
components) and a voltage source.
The resistors are connected in series
here and the voltage is given across
these two resistors.
This circuit is also termed as a potential
divider.
The input voltage is distributed among
the resistors (components) of the
voltage divider circuit. As a result, the
voltage division takes place. If you’re
looking for help on the calculation for
voltage division, you can use our
voltage divider calculator.
Current Divider
A current divider is defined as a linear
circuit that produces an output current
that is a fraction of its input current. This
is achieved through the connection of
two or more circuit elements connected
in parallel, the current in each branch
will always divide in such a way that the
total energy expended in a circuit is
minimum.
In other words, in a parallel circuit, the
supply current splits into a number of
parallel paths. It is also known as the
“current divider rule” or “current divider
law”.
A parallel circuit is often called current
divider in which terminals of all the
components are connected in such a
way that they share the same two end
nodes. These result in different parallel
paths and branches for the current to
flow through it.
externally disconnected,
which
is
equivalent to a resistance R=∞ . This
means that zero current can flow
between the two terminals, regardless
of any voltage difference. (Note that
Voltage Selector
very high voltages can cause arcs of
A voltage selector provides a means to
current to flow even over large air or
select the internal circuit that will match
vacuum gaps!)
the incoming voltage level (either 110 or
230V). For companies that design
equipment for both domestic and
overseas markets, this allows them to
design the internal wiring for specific
voltages for different markets, when the
equipment is not capable of accepting
a wide range of voltages (e.g. 90V to
264V).
With the voltage selector switch, the
end user can tell the equipment which
Circuit (Active & Passive)
Active circuits are circuits with energy
supplying
components
in
them,
whereas passive circuits can only
consume (or preserve) energy.
Common
examples
components include:
•
•
•
wiring system to use based on where
current to the correct components to
•
handle the voltage required.
Short Circuit
A short circuit implies that the two
terminals are externally connected with
resistance R=0 , the same as an ideal
wire. This means there is zero voltage
difference for any current value. (Note
that
real
wires
have
non-zero
resistance!)
•
and
active
as
DC
All different types of
transistors (such as
bipolar
junction
transistors,
MOSFETS,
FETs, and JFET)
Diodes (such as Zener
diodes,
photodiodes,
Schottky diodes, and
LEDs)
Components incapable of controlling
current by means of another electrical
signal are called passive devices.
Open Circuit
An open circuit implies that the two
terminals
Voltage sources
Current sources
Generators (such
alternators
generators)
the switch is set. The switch directs the
of
are
points
are
As the name ‘passive’ suggests –
passive devices do not provide gain or
amplification. Passive components
cannot amplify, oscillate, or generate
an electrical signal.
Common
examples
components include:
of
passive
of
resistors,
Resistors
Inductors
Capacitors
Transformers
•
•
•
•
Resistive Network
is
an
interconnection
arranged
in
a
particular
pattern,
designed to perform a specific function
within
an
electronic
circuit.
These
networks are fundamental building
blocks in electronic devices and are
used to control voltages and currents.
They are used in the design of voltage
dividers, where they divide the input
voltage into smaller voltages.
They also play a crucial role in creating
RC (Resistor-Capacitor) circuits, used
in filters and timers.
Moreover, in analog electronics, these
networks are used in biasing circuits,
feedback networks, and impedance
matching.