Transcript ELECTROMAGNETICS 11

Electromagnetics
11-ES 207
L- T-P : 3-1-0
Credits: 4
Bhanu Prakash
Assoc. Professor
EEE Department
Session Learning Objectives: (points to be discussed)
 Need of “Electromagnetics (course)”
 Principle of generation
 Classification
 Sources of Electromagnetic waves
 Advantages & Disadvantages
 Applications
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Need of “Electromagnetics” Study ?
Electromagnetic fields (EMF) are all around us. We
need them to see, to listen to radio and watch
television, to communicate using mobile phones,
and to run motors, fans, relays etc.
we generate them every time we turn on a light
switch or use an electric appliance.
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Faraday's law of induction: (1830s)
Explanation-1
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Explanation-2
How to produce/ generate/
induce Electric Field ?
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Electric Fields:
 Electric fields arise from voltage (Current Carrying conductor)
 An electric field can be present even when a device is
switched off.
 Field strength decreases with distance from the source.
 Most building materials shield electric fields to some extent.
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How to produce/ generate/
induce Magnetic Field ?
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Magnetic Fields:
 Magnetic fields arise from current flows.
 Magnetic fields exist as soon as a device is switched on and
current flows.
 Field strength decreases with distance from the sources.
 Magnetic fields are not attenuated by most materials.
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Which of the following is Electric field or
Magnetic field or both?
Fig.-2
Fig.-1
Fig.-3
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Fig.-4
Types of Electromagnetic Radiations
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AM and FM radio waves (including TV signals)
Cell phone communication links
Microwaves
Infrared radiation
Light
X-rays
Gamma rays
What distinguishes these from one another?
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i.e. Classification
Type
Frequency
Range
Extremely Low
Frequency
3 Hz – 3 KHz
Radio
Waves
3 KHz –
300 MHz
Microwaves
300 MHz –
300 GHz
Infrared
radiation
Ultraviolet
radiation
X-rays
300 GHz – 300
300 THz –
300 THz – 30 PHz
THz
30 PHz
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Gamma rays
30 PHz – 30
EHz
Is there any insulation for Current?
Is there any insulation for Field
(Flux) ?
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Which is most liking place in your Home?
Kitchen room
Hall
Bed room
Bathroom
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Sources of Electromagnetic fields
Frequency Range
3 Hz – 3 KHz
3 KHz – 300 MHz
Type
Common Sources
Power lines, appliances,
Extremely Low Frequency
electronics
AM/FM radio, television
Radio Waves
broadcasting, CB radios
300 MHz – 300 GHz Microwaves
300 GHz – 300 THz Infrared radiation
300 THz – 30 PHz
Ultraviolet radiation
300 THz – 30 PHz
30 PHz – 30 EHz
X-rays
Gamma rays
Cell phones, wireless internet,
satellite broadcasting, microwave
ovens, radar, medical imaging
Lasers, alarm systems, motion
detectors
Fluorescent and incandescent
lights
X-ray medical imaging
Nuclear material
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Sources of Electromagnetic fields
Contd……
 computers and related
 microwave ovens
equipment
 computer screens (especially
the older types),
 information networks
 electrical appliances
(including TV's)
 electronic equipment
 Cell phones
 cell phone masts
 radio and TV transmitters
 microwave transmitters or
ovens,
 house-wiring
 high and low voltage power
lines
 cars, motor cycles, buses,
trains, planes.
 high voltage transformers,
 transmission cables & Lines
 pylons.
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What are the sources of EM waves in this Lecture hall?
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Field distributions
Electromagnetic fields
inside a Motor
Electromagnetic fields inside
a desktop computer
The H-field on the whole
surface of an airplane
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Disadvantages
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Which is most liking place in your Home?
Kitchen room
Hall
Bed room
Bathroom
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Electromagnetic field radiation (EMF) is emanating from virtually every
single electrical appliance, computer, electric wire, and especially high
voltage lines (overhead and buried), which are carrying current.
EMF is specifically causing cancer in children and in older adults and may
be triggering countless other immune deficiency and psychological
diseases and disorders in anyone in close proximity.
Many scientists warn people not to live within 200 yards (190m) of high
voltage power lines.
Of 35 international research studies on electric
field radiation, 33 established a conclusive link
between brain tumors, leukemia, and other
forms of cancer.
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The Bedroom Is Often the Most Dangerous
Place In the Home
Many researchers and scientists now feel that electromagnetic
field radiation, both from within and without the bedroom, is
the single biggest factor in poor sleep. And poor health.
Look around your bedroom.
Is there a clock radio on the nightstand near your pillow?
A TV?
A stereo?
A cell phone below the pillow (bedmate)?
A Laptop near to you/ your bed?
Are there high voltage power lines with close to your residence?
All or any of these electric sources can ruin your sleep and can
substantially increase your risk of developing cancer and any
number of diseases, both psychological and physical.
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 While you sleep, your body relaxes and is unconscious. In this state
of vulnerability, research indicates you are 100-150 times more open
to the damage of electromagnetic radiation that when you are
awake. Children are often up to 1,000 times more sensitive to these
fields when they are asleep. (TV screen in your bedroom will radiate
energy all night...even after it has been unplugged. It can take hours
or even days for the built-up voltage in the television to dissipate. )
 Do not leave any thing plugged in while you sleep, even if it is
turned off. Outside high voltage power lines continually radiate EMF
24 hours a day.
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Biological Effects of Electromagnetic Radiation
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Protein Changes in Skin
Excited Brain Cells
DNA Damage
Brain Cell Damage
Aggressive Growth in Leukemia Cells
Increased Blood Pressure
Harmful Effects of ElectroMagnetic Radiation
Salivary Gland Cancer
Brain Tumour
 Lymphatic Cancer and Bone Marrow Cancer
 Miscarriage
 Asthma
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Bhanu Prakash @ K L University
Size of the Substations
11KV/132KV
132KV/33KV
132KV/11KV
33KV/11KV
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Bhanu Prakash @ K L University

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Easy to generate, use, and applicable in many implements.
Easy hand rules to understand flow direction, force, and polarity
too.
Can be used in incredibly small to very large situation (i.e.
pacemakers or trains)
Electromagnetic energy is clean. It is not polluting
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Applications:
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Motors and generators
Transformers
Relays
Electric bells
Loudspeakers
Magnetic recording and data storage equipment: tape
recorders, VCRs, hard disks
Scientific instruments such as MRI machines and mass spectrometers
Particle accelerators
Magnetic locks
Magnetic separation of material
Industrial lifting magnets
Electromagnetic suspension used for MAGLEV trains
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Applications:
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Contd….
Radars
Cooking (with microwaves)
Medical Imaging (X rays)
“Night Vision” (infrared)
Astronomy (radio, wave, IR, visible, UV, gamma)
Satellite Communication
TV Communication
Wireless Communication
Mobile Communication
Microwave Communication
This theory is also used in analysis and designing of antenna, transmission
lines and wave guides.
All that we experience through our eyes is conveyed by
electromagnetic radiation…
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Applications: (Medical)
Contd….
• Magnetic resonance imaging used in diagnostic. In this case is used
a static magnetic field (a few Tesla) with a radio frequency signal
superimposed
• Hyperthermia uses electromagnetic fields for the treatment of cancer
by means of tissue heating;
• Electric stimulation: the stimulation of the hippocampus by means of
electric field can be used in some brain therapy like Parkinson or
neurological diseases.
• Pulsed electromagnetic fields can affect the osteoblaste proliferation
for bone reparation and favorite the wound healing.
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Points discussed : (Summary)
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Doubts/Questions?
Doubt is worst Enemy!
If you still have enemies Send them to
[email protected]
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