GOOD FOR B.TECH STUDENTS

1. IMPORTANCE OF THE
SUBJECT

2. 2
What was learnt in Introduction to
Electromagnetic Fields
• Electromagnetics is the study of the effect
of charges at rest and charges in motion.
• Some special cases of electromagnetics:
– Electrostatics: charges at rest
– Magnetostatics: charges in steady motion (DC)
– Electromagnetic waves: waves excited by
charges in time-varying motion

3. What happens when electric and
magnetic fields change?
 A changing magnetic field creates a
changing electric field.

4. What happens when electric and
magnetic fields change?
 A changing magnetic field creates a
changing electric field  Faraday’s law.
 One example of this is a transformer which
transfers electric energy from one circuit to
another circuit.

5. What happens when electric and
magnetic fields change?
 A changing magnetic field creates a changing
electric field.
 One example of this is a transformer which
transfers electric energy from one circuit to
another circuit.
 In the main coil changing electric current produces a
changing magnetic field
 Which then creates a changing electric field in
another coil producing an electric current
 The reverse is also true.

6. Electromagnetic Waves…
 Do not need matter to transfer energy.

7. Electromagnetic Waves…
 Do not need matter to transfer energy.
 Are made by vibrating electric charges and
can travel through space by transferring
energy between vibrating electric and
magnetic fields.

8. Making Electromagnetic Waves
 When an electric charge vibrates, the electric
field around it changes creating a changing
magnetic field.

9. Making Electromagnetic Waves
 The magnetic and electric fields create each
other again and again.
 Maxwell theoretically showed from his equations
that an electromagnetic field can detach itself
from sources &propagate through space as a
field package, known as electromagnetic wave.

10. Making Electromagnetic Waves
 An EM wave travels in all directions. The figure
only shows a wave traveling in one direction.

11. Making Electromagnetic Waves
 The electric and magnetic fields vibrate at right
angles to the direction the wave travels so it is a
transverse wave.

12. What is the speed of EM waves?
 Material Speed
(km/s)
Vacuum 300,000
Air <300,000
Water 226,000
Glass 200,000
Diamond 124,000

13. What is the wavelength &
frequency of an EM wave?
 Wavelength= distance from crest to crest.

14. What is the wavelength &
frequency of an EM wave?
 Wavelength= distance from crest to crest.
 Frequency= number of wavelengths that
pass a given point in 1 s.

15. What is the wavelength &
frequency of an EM wave?
 Wavelength= distance from crest to crest.
 Frequency= number of wavelengths that
pass a given point in 1 s.
 As frequency increases, wavelength
becomes….

16. What is the wavelength &
frequency of an EM wave?
 Wavelength= distance from crest to crest.
 Frequency= number of wavelengths that
pass a given point in 1 s.
 As frequency increases, wavelength
becomes smaller.

17. The whole range of EM wave…
 Frequencies is called the
electromagnetic spectrum.

18. The whole range of EM wave…
 Frequencies is called the
electromagnetic spectrum.
 Different parts interact with matter in
different ways.

19. The whole range of EM wave…
 Frequencies is called the
electromagnetic spectrum.
 Different parts interact with matter in
different ways.
 The ones humans can see are called
visible light, a small part of the whole
spectrum.

20. As wavelength decreases,
frequency increases…

21. • Natural sources of electromagnetic fields
 Electromagnetic fields are present everywhere in our environment but
are invisible to the human eye.
 Electric fields are produced by the local build-up of electric charges in
the atmosphere associated with thunderstorms. Lightning is a
sudden electrostatic discharge during an electric
storm between electrically charged cloud and another cloud (CC
lightning), or between a cloud and the ground (CG lightning). The
charged regions within the atmosphere temporarily equalize
themselves through a lightning flash, commonly referred to as a strike if
it hits an object on the ground.
 The earth's magnetic field causes a compass needle to orient in a
North-South direction and is used for navigation.

22. • Human-made sources of electromagnetic fields
 Besides natural sources the electromagnetic spectrum also
includes fields generated by human-made sources:
 X-rays are employed to diagnose a broken limb after a sport
accident.
 The electricity that comes out of every power socket has
associated low frequency electromagnetic fields.
 And various kinds of higher frequency radiowaves are used
to transmit information – whether via TV antennas, radio
stations or mobile phone base stations.

23. Devices detect other frequencies:
 Antennae of a radio detects radio waves.

24. Devices detect other frequencies:
 Antenna of a radio detects radio waves.
 Radio waves are low frequency EM
waves with wavelengths longer than 1mm.

25. Devices detect other frequencies:
 Antennae of a radio detects radio waves.
 Radio waves are low frequency EM
waves with wavelengths longer than 1mm.
 These waves must be turned into sound
waves by a radio before you can hear
them.

26. What are microwaves?
 Microwaves are radio waves with wavelengths less than
30 cm and higher frequency & shorter wavelength.
 Cell phones and satellites use microwaves between 1
cm & 20 cm for communication.
 In microwave ovens, a vibrating electric field causes
water molecules to rotate billions of times per second
causing friction, creating TE which heats the food.

27. How does radar work?
 Radio Detecting And Ranging or radar is
used to find position and speed of objects
by bouncing radio waves off the object.

28. What is magnetic resonance
imaging?
 MRI scanners use strong magnetic fields
and radio waves to form images of the
body.

29. Infrared Waves
 EM with wavelengths between 1mm & 750
billionths of a meter.
 Used daily in remote controls, to read CD-
ROMs
 Every objects gives off infrared waves;
hotter objects give off more than cooler
ones. Satellites can identify types of
plants growing in a region with infrared
detectors

30. Visible Light
 Range of EM humans can see from 750
billionths to 400 billionths of a meter.
 You see different wavelengths as colors.
Blue has shortest
Red is the longest
Light looks white if all colors are present

31. Ultraviolet Waves
 EM waves with wavelengths from about
400 billionths to 10 billionths of a meter.
 Have enough energy to enter skin cells
Longer wavelengths – UVA
Shorter wavelengths – UVB rays
Both can cause skin cancer

32. Can UV radiation be useful?
 Helps body make vitamin D for healthy
bones and teeth
 Used to sterilize medical supplies & equip
 Detectives use fluorescent powder
(absorbs UV & glows) to find fingerprints

34. X Rays and Gamma Rays
 EM waves with
shortest wavelength &
highest frequency
 High Energy- go
through skin & muscle
 High level exposure
causes cancer

35. X Rays and Gamma Rays
 EM with wavelengths
shorter than 10
trillionths of a meter.
 Highest energy, can
travel through several
centimeters of lead.
 Both can be used in
radiation therapy to
kill diseased cells.
 The composite image
shows the all sky
gamma ray
background.

36. Radio Transmission
 Radio stations change sound to EM waves &
then your radio receiver changes the EM waves
back to sound waves again.

37. Television
 The basic idea of television is "radio with pictures".
 In other words, where radio transmits a
sound signal (the information being broadcast) through
the air, television sends a picture signal as well.
 You probably know that these signals are carried by
radio waves, invisible patterns
of electricity and magnetism that race through the air at
the speed of light (300,000 km or 186,000 miles per
second).

38. What is a cathode-ray tube?
 Many TVs and computer monitors display
images on a CRT, a sealed vacuum tube in
which beams of electrons are produced.
 CRT working involves understanding charge
motion in electric and magnetic fields.
 Basically a stream of electrons is accelerated by
an electric field &then deflected by a magnetic
field, to trace a point on the front surface of the
monitor & point by point a full image.

39. Telephones
 Sound waves microphone electric signal
radio waves transmitted to and from
microwave tower  receiver electric signal 
speaker sound wave

40. Communications Satellites
 Thousands of satellites
orbit Earth. A radio or
TV station sends
microwave signals to
the satellite which
amplifies the signal and
sends it back to a
different place on
Earth. Satellite uses dif
freq to send & receive.

41. Global Positioning System
 GPS is a system of 24 satellites, ground
monitoring stations and portable receivers
that determine your exact location on
Earth. GPS receiver measures the time it
takes for radio waves to travel from 4
different satellites to the receiver. The
system is owned and operated by the US
Dept of Defense, but the microwaves can
be used by anyone.

42. Applications
 RF communication
 Microwave Engineering
 Antennas
 Electrical Machines
 Satellite Communication
 Atomic and nuclear research
 Radar Technology
 Remote sensing
 EMI EMC
 Quantum Electronics
 VLSI

43. COURSE OBJECTIVES:
 Students will read and analyze different laws and
theorems to find electric field due to different charge
distributions.
 Student will read and analyze the effects of static
magnetic fields due to different current distributions.
 Students will understand the Maxwell equations, the
concepts of wave theory its propagation through various
media.
 Students will learn the concepts like polarization,
reflection, refraction and pointing vector.
 Students will get an exposure to the properties of
transmission line, electromagnetic wave propagation in
transmission line geometries.

44. COURSE OUTCOMES:
 Have the ability to use different laws and theorems to
find electric field due to different charge distributions
 Have the ability to understand the effects of static
magnetic fields due to different current distributions
 Grasp the importance of the Maxwell equations, the
concepts of wave theory its propagation through various
media
 Have the ability to understand the concepts like
polarization, reflection, refraction and pointing vector
 Have the ability to understand the properties of
transmission lines, electromagnetic wave propagation in
transmission line geometries.

45. COURSE PRE-REQUISITES:
1. Vector calculus
2. Co-ordinate systems

46. SYLLABUS WITH TEXT BOOKS & REFERENCE BOOKS.
SYLLABUS
UNIT I
ELECTROSTATICS: Introduction to 3-D orthogonal co ordinate transformations
and vector calculus , Coulomb’s Law and Electric Field Intensity, Electric Fields due
to continuous Charge Distributions, Electric Flux Density, Gauss Law and
Applications, Electric Potential, Relations Between E and V, Energy Density,
Convection and Conduction Currents, Dielectric Constant, Isotropic and
Homogeneous Dielectrics, Continuity Equation, Relaxation Time, Poisson’s and
Laplace’s Equations, Capacitances and energy density. Related problems.
UNIT II
MAGNETO STATICS: Introduction, Biot-Savart Law, Ampere’s Circuital Law and
Applications, Magnetic Flux Density, Magnetic Scalar and Vector Potentials, Forces
due to Magnetic Fields, Ampere’s Force Law, inductance and magnetic energy
density. Related problems.

47. UNIT III
MAXWELL’S EQUATIONS : Introduction, Faraday’s Law, Transformer and motional
emf, inconsistency of Ampere’s Law and Displacement Current Density, Maxwell’s
equations in differential, Integral form and word statements. Boundary conditions:
Dielectric-Dielectric and Dielectric-Conductor Interfaces. Related problems.
UNIT IV
ELECTROMAGNETIC WAVE EQUATIONS: Introduction, Applications of EM waves,
Wave equations for conducting, dielectric and lossless media, Uniform Plane Wave
(UPW) and general solution of UPW. Relations between E & H in UPW.
Characterization of conductors and dielectrics, wave propagation in good conductors
and good dielectrics, skin depth, polarization. Related problems.
UNIT V
ELECTROMAGNETIC WAVE CHARACTERISTICS : Introduction Normal and
Oblique incidence of UPW on perfect conductor and perfect dielectrics, Brewster
angle, critical angle and total internal reflection, surface impedance. Poynting Vector
and Poynting theorem – applications, Related problems.

48. UNIT VI
TRANSMISSION LINES: Types, Applications, equivalent circuit of two wire parallel
transmission lines, Primary constants, Line Equations, Secondary Constants,
Expressions for Characteristic Impedance, Propagation Constant, Phase and Group
Velocities, Infinite Line Concepts, Loss less and Low Loss Characterization, Distortion
– Condition for Distortion less and Minimum Attenuation, Input Impedance Relations,
SC and OC Lines, Reflection Coefficient, VSWR. UHF Lines as Circuit Elements; λ/4,
λ /2, λ/8 Lines . Smith Chart – Construction and Applications, Single stub. Related
problems.

49. TEXT BOOKS:
1. Electromagnetic Field Theory And Transmission Lines – GSN Raju, Pearson Education
3rd edition 2009.
2. Elements of Electromagnetics – Matthew N.O. Sadiku, Oxford Univ. Press, 4th ed.,
2007
REFERENCES:
1. Engineering Electromagnetics – Nathan Ida, Springer (India) Pvt. Ltd., New Delhi, 2nd
ed., 2005.
2. Electromagnetic Waves and Radiating Systems – E.C. Jordan and K.G. Balmain, PHI,
2nd Edition, 2000.
3. Engineering Electromagnetics by William H. Hayt Jr. and John A Buck, TMH, 7th
Edition.

50. SYLLABUS COVERED IN GATE
ELECTROMAGNETICS
Electrostatics; Maxwell’s equations: differential and integral forms and their interpretation,
boundary conditions, wave equation, Poynting vector; Plane waves and properties: reflection
and refraction, polarization, phase and group velocity, propagation through various media,
skin depth; Transmission lines: equations, characteristic impedance, impedance matching,
impedance transformation, Smith chart
SYLLABUS COVERED IN IES
ELECTROMAGNETIC THEORY
Analysis of electrostatic and magneto static fields; Laplace’s and Poisson’s equations; Boundary
value problems and their solutions; Maxwell’s equations; application to wave propagation in
bounded and unbounded media; Transmission lines : basic theory, standing waves, matching
applications.