The document provides an overview of key concepts in DC circuits, including Ohm's Law, internal resistance, and series and parallel circuit configurations. It explains Kirchhoff's current and voltage laws, defining essential terms such as active and passive elements, branches, and nodes. Various formulas and applications related to resistance and voltage are also discussed.

1. DC Circuits
Mr. C D Patil
Dept. of EE

2. Ohms Law
• Ohm's law states that the
current through a conductor
between two points is directly
proportional to the voltage
across the two points.
OR
• Ohm’s law states that the
voltage across a conductor is
directly proportional to the
current flowing through it,
provided all physical
conditions and temperature,
remain constant.

3. Internal Resistance of Source
• It is the resistance which
causes internal voltage drop in
the Source.
• All the practical voltage &
current sources are always
has internal resistance.
• Due to internal resistance the
terminal voltage is always less
than Source voltage.
• The voltage across terminals
of Cell or Battery is called as
Terminal Voltage.

4. Resistance in Series
• The same current flows
through each part of a series
circuit.
• The total resistance of a
series circuit is equal to the
sum of individual
resistances.
• Voltage applied to a series
circuit is equal to the sum of
the individual voltage drops.
• Total Resistance=
R1+R2+R3+…

5. Resistance in Series
• Voltage across resistance
R1= V1= I*R1
• Voltage across resistance
R2= V2= I*R2
• Voltage across resistance
R3= V3= I*R3
• Voltage across resistance
R4= V4= I*R4
• Total Voltage (V) =
V1+V2+V3+V4.
• Application- Decoration
Lighting

6. Resistance in Parallel
• Voltage: Voltage is equal
across all resistance in a
parallel circuit.
• Current: The total circuit
current is equal to the sum
of the individual branch
currents.
I= I1+I2+I3+….
• Total resistance=

7. Series- Parallel

8. Definition of Basic Terms
• Active Element- An element which can
generate or produce the energy is called as
Active element.
e.g.- Voltage Source, Current source, genearator
etc
• Passive element- An element which can not
generate energy is called as Passive element.
e.g.- Resistance, Inductance, Capacitance

9. Definition of Basic Terms
• Active Network- If a
network consist of an
energy source then it is
called as Active
network.
• Passive Network- If a
network does not have
an energy source then it
is called as Passive
network.

10. Definition of Basic Terms
• Branch- It is the group of
elements connected
between two junctions.
• Mesh/ Loop- It’s the
closed path formed in a
network which start &
end at same point
• Node/ Junction- It is the
common point on the
network where two or
more branches are
connected.

11. Definition of Basic Terms

12. Examples on Series- Parallel circuits

13. Examples on Series- Parallel circuits

14. Kirchhoff’s Current Law
• The algebraic sum of all
currents meeting at junction
point is equal to zero.
i.e. Σ I= 0
• At Junction,
Incoming current = Outgoing
current
• The total current entering a
junction or a node is equal
to the current leaving the
node.

15. Kirchhoff’s Voltage Law
• In any closed loop, the
algebraic sum of EMF’s &
algebraic sum of voltage
drops is equals to zero.
i.e. Σ EMF + Σ Voltage Drops
= 0
Σ EMF = Σ Voltage Drops
• In any closed loop network,
the total voltage around the
loop is equal to the sum of all
the voltage drops within the
same loop.

16. Kirchhoff’s Law Examples

17. Kirchhoff’s Law Examples

18. Kirchhoff’s Law Examples

19. Thank You!!!