This document provides an overview of basic electrical engineering concepts including charge, current, voltage, circuits, network elements, sources, superposition theorem, Thevenin's theorem, Norton's theorem, and maximum power transfer theorem. Key points include: - Current is the rate of charge flow measured in amperes. Voltage is the potential difference measured in volts. - Circuits contain both active elements that supply energy (sources) and passive elements that consume energy. - Superposition and source transformation theorems allow analysis of circuits containing multiple sources. - Thevenin's and Norton's theorems convert circuits to equivalent circuits with a single voltage or current source. - Maximum power is delivered to a load when

1. BASIC ELECTRICAL ENGINEERING
REE – 101/201
MOHAMMED WARIS SENAN
ASSISTANT PROFESSOR
DEPARTMENT OF ELECTRICAL ENGG.
JAHANGIRABAD INSTITUTE OF TECHNOLOGY
Jahangirabad Institute of Technology

2. CHARGE (Q)
 Charge is conserved: it is neither created nor destroyed
 Symbol: Q or q; units are coulomb (C)
 The smallest charge, the electronic charge, is carried by an electron
(−1.602×10-19 C) or a proton (+1.602×10-19 C)
 In most circuits, the charges in motion are electrons
A physical Property of matter by virtue of which it experiences a force when place in electromagnetic field

3. CURRENT AND CHARGE
Current is the rate of charge flow:
1 ampere = 1 coulomb/second (or 1 A = 1 C/s)

4. CURRENT AND CHARGE
Current is designated by both magnitude and direction
The above two currents are same
3A
-3A

5. VOLTAGE (V)
Potential: Work done in bringing a unit positive charge from infinity to a point inside an electrical field.
Q
W

(coulomb)Charge
(joule)Workdone
Potential Unit of Potential is J/C or Volts
The difference in potentials of two points inside an electrical field is termed as Voltage denoted by ‘V’

6. • When 1J of work is required
to move 1C of charge from A
to B, there is a voltage of 1
volt between A and B.
• Voltage (V or v) across an
element requires both a
magnitude and a polarity.
• Example: (a)=(b), (c)=(d)
VOLTAGE (V)

7. • The power required to push a current i (C/s)
into a voltage v (J/C) is p = vi ( J/s = W).
• When power is positive, the element is
absorbing energy.
• When power is negative, the element is
supplying energy.
POWER (P = VI)

8. • Electrical Circuit – Any closed path containing electrical elements.
• Electrical Network – Combination of different electrical elements which may
or may not have closed path.
ELECTRICAL CIRCUIT & NETWORK

9. • Active : Need Activation and Deliver Energy
e.g. – Voltage Source, Current Source etc.
• Passive : Consumes Energy
e.g. – Resistor, Inductor etc.
ACTIVE AND PASSIVE ELEMENTS

10. Voltage and Current Sources
Independent Sources
Magnitude of Voltage or Current does
not depend upon any circuit parameter
Dependent Sources
Magnitude of Voltage or Current depend
upon internal circuit parameter
Voltage Controlled
Current Controlled
VOLTAGE AND CURRENT SOURCES

11. DEPENDENT SOURCES
Dependent current sources (a) and (b) maintain a current specified by another circuit variable.
Dependent voltage sources (c) and (d) maintain a voltage specified by another circuit variable.
Example

12. DEPENDENT SOURCES
Dependent current sources (a) and (b) maintain a current specified by another circuit variable.
Dependent voltage sources (c) and (d) maintain a voltage specified by another circuit variable.
Example

14. SUPERPOSITION THEOREM
• Voltage across (or current through) an element
• Determined by summing voltage (or current) due to each independent source
• All sources (except dependent sources) other than the one being
considered are eliminated

15. SUPERPOSITION THEOREM
• Replace current sources with opens
• Replace voltage sources with shorts

16. SUPERPOSITION THEOREM
• Circuit may operate at more than one frequency at a time
• Superposition is the only analysis method that can be used in this case
• Reactances must be recalculated for each different frequency

17. SUPERPOSITION THEOREM
• Superposition theorem can be applied only to voltage and current
• It cannot be used to solve for total power dissipated by an element
• Power is not a linear quantity
• Follows a square-law relationship

18. SUPERPOSITION FOR DEPENDENT SOURCES
• If controlling element is external to the circuit under consideration
• Method is the same as for independent sources

19. SUPERPOSITION FOR DEPENDENT SOURCES
• Simply remove sources one at a time and solve for desired voltage or current
• Combine the results

20. SUPERPOSITION FOR DEPENDENT SOURCES
• If the dependent source is controlled by an element located in the circuit
• Analysis is different
• Dependent source cannot be eliminated

21. THEVENIN’S THEOREM
• Converts an ac circuit into a single ac voltage source in series with an equivalent
impedance
• First, identify and remove the element or elements across which the equivalent
circuit is to be found

22. THEVENIN’S THEOREM
• Label two open terminals
• Set all sources to zero
• Replace voltage sources with shorts
• Current sources with opens

23. THEVENIN’S THEOREM
• Calculate the Thévenin equivalent impedance
• Replace the sources and determine open-circuit voltage

24. THEVENIN’S THEOREM
• If more than one source is involved
• Superposition may be used
• Draw resulting Thévenin equivalent circuit
• Including the portion removed

25. NORTON’S THEOREM
• Converts an ac network into an equivalent circuit
• Consists of a single current source and a parallel impedance
• First, identify and remove the element or elements across which the Norton circuit
is to be found

26. NORTON’S THEOREM
• Label the open terminals
• Set all sources to zero

27. NORTON’S THEOREM
• Determine Norton equivalent impedance
• Replace sources and calculate short-circuit current

28. NORTON’S THEOREM
• Superposition may be used for multiple sources
• Draw resulting Norton circuit
• Including portion removed

29. THEVENIN AND NORTON CIRCUITS
• Possible to find Norton equivalent circuit from Thévenin equivalent circuit
• Use source transformation method
• ZN = ZTh
• IN = ETh/ZTh

30. THEVENIN’S AND NORTON’S THEOREMS
• If a circuit contains a dependent source controlled by an element outside the area of
interest
• Previous methods can be used to find the Thévenin or Norton circuit

31. THEVENIN’S AND NORTON’S THEOREMS
• If a circuit contains a dependent source controlled by an element in the circuit
• Other methods must be used

32. THEVENIN’S AND NORTON’S THEOREMS
• If a circuit has a dependent source controlled by an element in the circuit
• Use following steps to determine equivalent circuit

33. THEVENIN’S AND NORTON’S THEOREMS
• First
• Identify and remove branch across equivalent circuit is to be determined
• Label the open terminals

34. THEVENIN’S AND NORTON’S THEOREMS
• Calculate open-circuit voltage
• Dependent source cannot be set to zero
• Its effects must be considered
• Determine the short-circuit current

35. THEVENIN’S AND NORTON’S THEOREMS
• ZN = ZTh = ETh/IN
• Draw equivalent circuit, replacing the removed branch

36. THEVENIN’S AND NORTON’S THEOREMS
• A circuit may have more than one independent source
• It is necessary to determine the open-circuit voltage and short-circuit current due to
each independent source

37. MAXIMUM POWER TRANSFER THEOREM
• Maximum power
• Delivered to a load when the load impedance is the complex conjugate of the Thévenin or
Norton impedance

38. MAXIMUM POWER TRANSFER
THEOREM
• ZTh = 3 + j4 ZL = ZTh* = 3 - j4
• ZTh = 10 30° ZL = ZTh* = 10 -30°

39. MAXIMUM POWER TRANSFER THEOREM
• If the ZL is the complex conjugate of ZTh or ZN
 
N
2
N
2
N
max
Th
2
Th
max
2
Th
2
Th
4
4
R
ZI
P
R
E
P
RR
RE
P
L
L
L





40. RELATIVE MAXIMUM POWER
• If it is not possible to adjust reactance part of a load
• A relative maximum power will be delivered
• Load resistance has a value determined by
 22
ThTh XXRRL 