ABSTRACT:

The technology used for wireless power

transmission is known as witricity. Wireless

power transmission is not a new idea,

Nikola Tesla proposed theories of wireless

power transmission in the late 1800s and

early 1900s. Tesla's work was impressive,

but it did not immediately lead to wide

spread practical methods for wireless power

transmission. Since then many researchers

have developed several techniques for

moving electricity over long distances

without wires. Some exist only as theories or

prototypes, but others are already in use. In

2006 researchers at Massachusetts Institute

of Technology led by Marine Soijacic

discovered an efficient way to transfer

power between coils separated by a few

meters. They have dubbed this technology as

witricity

.

Witricity is based upon coupled resonant

objects. Two resonant objects of the same

resonant frequency tend to exchange energy

efficiently, while not interchanging the

surroundings. The researchers demonstrate

the ability to transfer 60W with

approximately 40% efficiency over distance

in excess of 2 meters. Currently the project

is looking for power transmission in the

range of 100watts. As witricity is in the

development stage, lots of work is to be

done in improving the range of power

transmission and efficiency.

1.INTRODUCTION

what it can make peoples lives easier, it can

add a lot of clutter in the If we are

particularly organized and good with tie

wrap then also a few dusty power cord

tangles around our home. We have even had

to follow one particular cord through the

seemingly impossible snarl to the outlet

hoping that the plug pull will be the right

one. This is one of the downfalls of

Fig.1:wireless electricity

electricity. While it can make people's

process. For these reasons, scientists have

tried to develop methods of wireless power

transmission that could cut the clutter or

lead to clean sources of electricity. Wireless

power transmission is not a new idea. Many

researchers developed several methods for

wireless power transmission. But witricity is

a new technology used for wireless power

transmission. By the use of this technology

transmission of electrical energy to remote

objects without wires can be possible. The

inventors of witricity are the researchers

from Massachusetts Institute of

Technology(MIT).

Fig.2:Expermiment on witricity

They developed a new technology for

wireless electricity transmission and this is

based upon the coupled resonant objects. In

this resonant magnetic fields are used. So

the wastage of power is reduced. The system

consists of witricity transmitters and

receivers. The transmitters and receivers

contain magnetic loop antennas made of

copper coils and they are tuned to the same

frequency.

2.HISTORY

While Tesla was the first person to demonstrate

the practical possibilities of wireless power in

1899, today, commercially there is little more

than electric toothbrushes and charger mats

available, and in both technologies the

toothbrush, phone, and other small devices

need to be extremely close to their chargers.

Wireless power transmission as an

alternative to transmission line power

distribution (our current system of electric

power distribution) was first proposed and

demonstrated by Nikola Tesla. In 1899,

Tesla demonstrated wireless power

Fig.3:fluorescent lamp

transmission by powering a field of

fluorescent lamps located twenty-five miles

from their power source without using

wires. As impressive and forward thinking

as Tesla's work was, at that time is was

actually cheaper to build coppertransmission

lines rather than build the type of power

generators that Tesla's experiments required.

Tesla ran out of research funding and at that

time a practical and cost efficient method of

wireless power distribution could not be

2

develoThis team from MIT belonged to the

Department of Physics, Department of

Electrical Engineering and Computer

Science and the Institute for Soldier

Nanotechnologies. The members of this

team were Andre Kurs, Aristeidis Karalis,

Prof. Peter Fisher, Robert Moffatt and Prof.

John Joannopoulos. The leader of this team

of researchers was Prof. Marin Soljacic.

fig.3:MITteam

It was Prof. Marin Soljacic who provided the

inspiration for the experiment and

invention of witricity. It was while standing

in the kitchen one night, that on staring at

his mobile phone that he had thought it

would be nice if his mobile phone would

take care of its own charging instead of him

having to periodically charge it.

He then tried out his experiment using two

coils of copper, where one was connected

to a receiver, and the other to a transmitter.

With the help of these two coils of copper,

the inventors of witricity managed to

transmit power across seven feet through

the air to instantly light up a lightbulb.

Though witricity worked only distances up

till 9 feet at its inception, the inventors

believed that it was possible to charge a

battery that was located at a distance of a

few yards from the power source that was

connected to the receiving coil. They state

that it would be sufficient to place a source

in each room to provide power to the whole

house.

3.WiTricity Technology: The Basics

The experimental design consisted of two

copper coils, each a self-resonant system.

One of the coils, connected to an AC power

supply, was the resonant source. The other

coil, the resonant capture device, was

connected to a 60 watt light bulb. The power

source and capture device were suspended in

mid-air with nylon thread, at distances that

ranged from a few centimeters to over 2.5

meters (8.2 ft).  Not only was the light bulb

illuminated, but the theoretical predictions

of high efficiency over distance were proven

experimentally.

By placing various objects between the

source and capture device, the team

demonstrated how the magnetic near field

3

can transfer power through certain materials

and around metallic obstacles.

Thus Prof. Soljačić’s dream of finding a

method to wirelessly connect mobile electric

devices to the existing electric grid was

realized. WiTricity Corp. was soon launched

to carry this technology forward from the

MIT laboratories to commercial production.

Fig.4:witricity technology

3.1:Electricity: The flow of electrons (current)

through a conductor (like a wire), or charges

through the atmosphere (like lightning). A

convenient way for energy to get from one

place to another place

3.2:Magnetism: A fundamental force of

nature, which causes certain types of

materials to attract or repel each other.

Permanent magnets, like the ones on your

refrigerator and the earth’s magnetic field,

are examples of objects having constant

magnetic fields.

Fig.5:magnetism

Oscillating magnetic fields vary with time,

and can be generated by alternating current

(AC) flowing on a wire. The strength,

direction, and extent of magnetic fields are

often represented and visualized by

drawings of the magnetic field lines.

3.3:Electromagnetism: A term for the

interdependence of time-varying electric and

magnetic fields. For example, it turns out that

an oscillating magnetic field produces an

electric field and an oscillating electric field

produces a magnetic field.

Fig.6:Electro magnetism

As electric current, I, flows in a wire, it gives rise

to a magnetic field, B, which wraps around the

4

wire. When the current reverses direction, the

magnetic field also reverses its direction.

3.4:Magnetic Induction: A loop or coil of

conductive material like copper, carrying an

alternating current (AC), is a very efficient

structure for generating or capturing a magnetic

field.If a conductive loop is connected to an AC

power source, it will generate an oscillating

magnetic field in the vicinity of the loop. A

second conducting loop, brought close enough

to the first, may “capture” some portion of that

oscillating magnetic field, which in turn,

generates or induces an electric current in the

second coil. The current generated in the

second coil may be used to power devices. This

type of electrical power transfer from one loop

or coil to another is well known and referred to

as magnetic induction. Some common examples

of devices based on magnetic induction are

electric transformers and electric generators.

Fig.7:Magnetic induction

3.5:Energy/Power Coupling: Energy

coupling occurs when an energy source has

a means of transferring energy to another

object. One simple example is a locomotive

pulling a train car—the mechanical coupling

between the two enables the locomotive to

pull the train, and overcome the forces of

friction and inertia that keep the train still—

and, the train moves. Magnetic coupling

occurs when the magnetic field of one

object

Fig.8:Energy/power coupling

interacts with a second object and induces

an electric current in or on that object. In

this way, electric energy can be transferred

from a power source to a powered device.

In contrast to the example of mechanical

coupling given for the train, magnetic

coupling does not require any physical

contact between the object generating the

energy and the object receiving or capturing

that energy.

3.6:Resonance: Resonance is a property

that exists in many different physical

5

systems. It can be thought of as the natural

frequency at which energy can most

efficiently be added to an oscillating system.

A playground swing is an example of an

oscillating system involving potential energy

and kinetic energy. The child swings back

and forth at a rate that is determined by the

length of the swing. The child can make the

swing go higher if she properly coordinates her

arm and leg action with the motion of the

swing. The swing is oscillating at its resonant

frequency and the simple movements of the

child efficiently transfer energy to the system.

Another example of resonance is the way in

which a singer can shatter a wine glass by

singing a single loud, clear note.

In this example, the wine glass is the resonant

oscillating system. Sound waves traveling

through the air are captured by the glass, and

the sound energy is converted to mechanical

vibrations of the glass itself. When the singer

hits the note that matches the resonant

frequency of the glass, the glass absorbs energy,

begins vibrating, and can eventually even

shatter. The resonant frequency of the glass

depends on the size, shape, thickness of the

glass, and how much wine is in it.

3.7:Resonant Magnetic Coupling: Magnetic

coupling occurs when two objects exchange

energy through their varying or oscillating

magnetic fields. Resonant coupling occurs when

the natural frequencies of the two objects are

approximately the same.

Fig.9:Rsonant magnetic coupling

4.WiTricity Technology:

WiTricity power sources and capture devices

are specially designed magnetic resonators that

efficiently transfer power over large distances

via the magnetic near-field. These proprietary

source and device designs and the electronic

systems that control them support efficient

energy transfer over distances that are many

times the size of the sources/devices

themselves.

Understanding how it works is a bit more

involved, but it doesn’t require an engineering

6

Fig.10:witricity technology

you play a The WiTricity power source, left, is

connected to AC power. The blue lines

represent the magnetic near field induced by

the power source. The yellow lines represent

the flow of energy from the source to the

WiTicity capture coil, which is shown powering

a light bulb. Note that this diagram also shows

how the magnetic field (blue lines) can wrap

around a conductive obstacle between the

power source and the capture device.

5:HOW IT WORKS

Wireless light: Researchers used magnetic

resonance coupling to power a 60-watt light

bulb. Tuned to the same frequency, two 60-

centimeter copper coils can transmit

electricity over a distance of two meters,

through the air and around an obstacle.

The researchers built two resonant copper

coils and hung them from the ceiling, about

two meters apart.

When they plugged one coil into the wall,

alternating current flowed through it,

Creating a magnetic field.

The second coil, tuned to the same

frequency and hooked to a light bulb,

reso¬nated with the magnetic field,

generating an electric current that lit up the

bulb--even with a thin wall between the

coils.

Fig:11:working of witricity

There are two important terms to explain how

wireless electricity works in, for example, an

electric toothbrush, it works by "inductive

coupling" and "electromagnetism". According to

the Wireless Power Consortium, "Wireless

charging, also known as inductive charging, is

based on a few simple principles. The

technology requires two coils: a transmitter and

a receiver. An alternating current is passed

through the transmitter coil, generating a

magnetic field. This in turn induces a voltage in

the receiver coil; this can be used to power a

mobile device or charge a battery."To explain

further, whenever you direct an electrical

current through a wire there is a natural

7

phenomena that occurs, that a circular

magnetic field is created around the wire. And if

you loop/coil that wire that wire's magnetic

field gets stronger. If you take a second coil of

wire that does not have an electrical current

passing through it, and place that coil within the

magnetic field of the first coil, the electric

current from the first coil will travel through the

magnetic field and started running through the

second coil, that's inductive coupling.In an

electric toothbrush, the charger is connected to

a wall outlet that sends an electric current to a

coiled wire inside the charger creating a

magnetic field. There is a second coil inside of

the toothbrush, when you place the toothbrush

inside of its cradle to be charged the electric

current passes through the magnetic field and

sends electricity to the coil inside the

toothbrush, that coil is connected to a battery

which gets charged.The power exchange

efficiency of some induction systems is

improved by utilizing resonant circuits. These

so-called resonantly enhanced induction

techniques are used in certain medical implants

and high-frequency RFIDs for example.

However, to the best of our knowledge,

WiTricity’s founding technical team was the first

to discover that by specially designing the

magnetic resonators, one could achieve strong

coupling and highly efficient energy exchange

over distances much larger than the size of the

resonator coils, distances very large compared

to traditional schemes.

object to vibrate when energy of a certain

frequency is applied. Two resonant objects

of the same frequency tend to couple very

strongly." Resonance can be seen in musical

instruments for example. "Whtune on one,

then another instrument with the same

acoustic resonance will pick up that tune, it

will visibly vibrate,"

Instead of using acoustic vibrations, system

exploits the resonance of electromagnetic

waves. Electromagnetic radiation includes

radio waves, infrared and X-rays. Typically,

systems that use electromagnetic radiation,

such as radio antennas, are not suitable for

the efficient transfer of energy because they

scatter energy in all directions, wasting large

amounts of it into free space.

To overcome this problem, the team

investigated a special class of "non-

radiative" objects with so-called "long-lived

resonances".

When energy is applied to these objects it

remains bound to them, rather than escaping

to space. "Tails" of energy, which can be

many metres long, flicker over the surface.

If another resonant object is brought with

the same frequency close enough to these

tails then it turns out that the energy can

8

tunnel from one object to another.

Hence, a simple copper antenna designed to

have long-lived resonance could transfer

energy to a laptop with its own antenna

resonating at the same frequency. The

computer would be truly wireless.

Any energy not diverted into a gadget or

appliance is simply reabsorbed. The systems

that are described would be able to transfer

energy over three to five metres.

6:WiTricity is More Than...

6.1:Traditional Magnetic Induction

At first glance, WiTricity’s technology for power

transfer appears to be traditional magnetic

induction, such as is used in power

transformers, where conductive coils transmit

power to each other wirelessly, over very short

distances. In a transformer, an electric current

running in a sending coil (or “primary winding”)

induces another current in a receiving coil (or

“secondary winding”). The two coils must be

very close together, and may even overlap, but

the coils do not make direct electrical contact

with each other. However, the efficiency of the

power exchange in traditional magnetic

induction systems drops by orders of magnitude

when the distance between the coils becomes

larger than their sizes. In addition to electric

transformers, other devices based on traditional

magnetic induction include rechargeable

electric toothbrushes, and inductive “charging

pads” which require that the object being

charged be placed directly on top of, or very

close to, the base or pad supplying the power.

The power exchange efficiency of some

induction systems is improved by utilizing

resonant circuits. These so-called resonantly

enhanced induction techniques are used in

certain medical implants and high-frequency

RFIDs for example. However, to the best of our

knowledge, WiTricity’s founding technical team

was the first to discover that by specially

designing the magnetic resonators, one could

achieve strong coupling and highly efficient

energy exchange over distances much larger

than the size of the resonator coils, distances

very large compared to traditional schemes.

In addition to electric transformers, other

devices based on traditional magnetic

induction include rechargeable electric

toothbrushes, and inductive “charging pads”

which require that the object being charged

be placed directly on top of, or very close to,

the base or pad supplying the power.The

power exchange efficiency of some

induction systems is improved by utilizing

resonant circuits. These so-called resonantly

enhanced induction techniques are used in

certain medical implants and high-frequency

RFIDs for example. However, to the best of

our knowledge, WiTricity’s founding

9

technical team was the first to discover that

by specially designing the magnetic

resonators, one could achieve strong

coupling and highly efficient energy

exchange over distances much larger than

the size of the resonator coils, distances very

large compared to traditional schemes.

Fig.12: An electric toothbrush

6.2:Radiative power transfer

A microwave oven utilizes microwave

radiation to cook food.

Fig.13: A microwave oven utilizes

microwave radiation to cook food.

WiTricity’s technology for power transfer is

non-radiative and relies on near-field

magnetic coupling. Many other techniques

for wireless power transfer rely on radiative

techniques, either broadcasted or narrow

beam (directed radiation) transmission of

radio, or light waves.  Broadcasted radiation

of radio frequency energy is commonly used

for wireless information transfer because

information can be transmitted over a wide

area to multiple users. The power received

by each radio or wireless receiver is

miniscule, and must be amplified in a

receiving unit using an external power

supply. Because the vast majority of

radiated power is wasted into free space,

radio transmission is considered to be an

inefficient means of power transfer.   Note

that while more energy can be supplied to

the receiver by “cranking up the power” of

the transmitters in these systems, such high

power levels may pose a safety hazard and

may interfere with other radio frequency

devices.  “Directed radiation”, using highly

directional antennas, is another means of

using radio transmission to beam energy

from a source to a receiver. However,

directed radiation—in particular microwave

radiation—may interact strongly with living

organisms and certain metallic objects. Such

10

energy transfer methods may pose safety

hazards to people or objects that obstruct the

line-of-sight between the transmitter and

receiver.  These limitations make directed

radio transmission impractical for delivering

substantial levels of wireless power in a

typical consumer, commercial, or industrial

application. In fact, defense researchers are

exploring the use of directed energy systems

to deliver lethal doses of power to targets in

space and on the battlefield

Fig.14: The June 5, 1975 NASA JPL

Goldstone

6.3

:MagneticResonanceImaging(MRI):

Fig.15: MRI machines

MRI machines use “magnetic resonance

imaging” to produce diagnostic images of soft

tissue.Many people assume that WiTricity’s

“Resonant Magnetic Coupling” must be similar

to magnetic resonance imaging (MRI)

technology, however, the technologies are

similar in name only. MRI is, as its name

suggests, a technology for using magnetism as a

basis for diagnostic imaging of soft tissue in the

human body. It utilizes a strong DC magnet to

orient the magnetic fields of atoms within

tissues, and radio frequency fields to

manipulate those atoms in a selective way, so

that tissues and structures can be imaged

clearly. The “resonance” referred to in “MRI”

refers to the resonance of atomic structures.

MRI is not considered to be a method for

wireless power transfer.

7:Features and benifits

11

7.1:Highly Resonant Strong Coupling

Provides High Efficiency Over Distance:

WiTricity's mode of wireless power transfer

is highly efficient over distances ranging

from centimeters to several meters. We

define efficiency as the amount of usable

electrical energy that is available to the

device being powered, divided by the

amount of energy that is drawn by the

WiTricity source. In many applications,

efficiency can exceed 90%. And WiTricity

sources only transfer energy when it is

needed. When a WiTricity powered device

no longer needs to capture additional

energy, the WiTricity power source will

automatically reduce its power consumption

to a power saving “idle” state. Contact

WiTricity to learn the efficiency and

distance ranges that can be achieved in your

applications.

Fig.16:Highly reasonating

coupling7.2:Energy Transfer via Magnetic

Near Field Can Penetrate and Wrap Around

Obstacles

The magnetic near field has several

properties that make it an excellent means of

transferring energy in a typical consumer,

commercial, or industrial environment. 

Most common building and furnishing

materials, such as wood, gypsum wall board,

plastics, textiles, glass, brick, and concrete

are essentially “transparent” to magnetic

fields—enabling WiTricity technology to

efficiently transfer power through them.  In

addition, the magnetic near field has the

ability to “wrap around” many metallic

obstacles that might otherwise block the

magnetic fields.  WiTricity’s applications

engineering team will work with you to

address the materials and environmental

factors that may influence wireless energy

transfer in your application.

7.3:Non-Radiative Energy Transfer is

Safe for People and Animals

WiTricity’s technology is a non-radiative

mode of energy transfer, relying instead on

the magnetic near field. Magnetic fields

interact very weakly with biological

12

organisms—people and animals—and are

scientifically regarded to be safe. Professor

Sir John Pendry of Imperial College

London, a world renowned physicist,

explains:  “The body really responds

strongly to electric fields, which is why you

can cook a chicken in a microwave.  But it

doesn't respond to magnetic fields. As far as

we know the body has almost zero response

to magnetic fields in terms of the amount of

power it absorbs."  Evidence of the safety of

magnetic fields is illustrated by the

widespread acceptance and safety of

household magnetic induction cooktops.  

Through proprietary design of the WiTricity

source, electric fields are almost completely

contained within the source. This design

results in levels of electric and magnetic

fields which fall well within regulatory

guidelines. Thus WiTricity technology

doesn’t give rise to radio frequency

emissions that interfere with other electronic

devices, and is not a source of electric and

magnetic field levels that pose a risk to

people or animals.  Limits for human

exposure to magnetic fields are set by

regulatory bodies such as the FCC, ICNIRP,

and are based on broad scientific and

medical consensus. WiTricity technology is

being developed to be fully compliant with

applicable regulations regarding magnetic

fields and electromagnetic radiation.

7.4:Scalable Design Enables Solutions from

milliwatts to Kilowatts

WiTricity systems can be designed to handle

a broad range of power levels. The benefits

of highly efficient energy transfer over

distance can be achieved at power levels

ranging from milliwatts to several kilowatts.

This enables WiTricity technology to be

used in applications as diverse as powering a

wireless mouse or keyboard (milliwatts) to

recharging an electric passenger vehicle

(kilowatts). WiTricity technology operates in

a “load following” mode, transferring only

as much energy as the powered device

requires.

7.5:Flexible Geometry Allows WiTricity

Devices to be Embedded Into OEM

Products

WiTricity technology is being designed so

that it can be easily embedded into a wide

variety of products and systems. The physics

of resonant magnetic coupling enables

WiTricity engineers to design power sources

and devices of varying shapes and sizes, to

match both the packaging requirements and

the power transfer requirements in a given

13

OEM application. WiTricity has designed

power capture devices compact enough to fit

into a cell phone.OEM application.

WiTricity has designed power capture

devices compact enough to fit into a cell

phone.

8:WiTricity Intellectual Property

WiTricity is exclusive licensee of MIT

patents for Wireless Energy Transfer. Our

founder, MIT professor Marin Soljačić, was

the leader of the MIT research team that

developed WiTricity technology. This

includes the MIT patents for highly resonant

magnetic coupling as well as many energy

transfer system improvements. Since the

original discovery, WiTricity Corporation

has filed for patents on dozens of its own

innovations, including improvements to the

technology, as well as a large number of

products and applications that use the

technology. The MIT and WiTricity patents

are available for licensing for interested

parties. Please contact us to discuss potential

licensing agreements.Below is a partial list

of our issued patents and pending patent

applications.

9:WiTricity Products

WiTricity’s wireless power transfer

technology can be applied in a wide variety

of applications and environments. The

ability of our technology to transfer power

safely, efficiently, and over distance can

improve products by making them more

convenient, reliable, and environmentally

friendly. WiTricity technology can be used

to provide:

9.1:Direct Wireless Power—when all the

power a device needs is provided wirelessly,

and no batteries are required. This mode is

for a device that is always used within range

of its WiTricity power source.

9.2:Automatic Wireless Charging—when

a device with rechargeable batteries charges

itself while still in use or at rest, without

requiring a power cord or battery

replacement. This mode is for a mobile

device that may be used both in and out of

range of its WiTricity power source.

WiTricity technology is designed to be

directly embedded in the products and

systems of Original Equipment

Manufacturers (OEM's). If your company is

an OEM, you may be interested in our

developement kits which will allow you to

evaluate and adapt WiTricity wireless power

14

transfer to your own products, or you may

prefer a custom engagement with our in-

house research and development

department. Either way, we encourage you

to contact us to discuss your application in

more detail.

If you are a consumer eager to purchase

products that are WiTricity enabled, please

check back later at our website to learn

about products that you can purchase with

WiTricity inside!

10:Applications

1. Automatic wireless charging of mobile

electronics (phones, laptops, game

controllers, etc.) in home, car, office,

Wi-Fi hotspots … while devices are in

use and mobile.

2. Direct wireless powering of

stationary devices (flat screen TV’s,

digital picture frames, home theater

accessories, wireless loud speakers,

etc.) … eliminating expensive

custom wiring, unsightly cables and

“wall-wart” power supplies.

3. Direct wireless powering of desktop

PC peripherals: wireless mouse,

keyboard, printer, speakers, display,

etc… eliminating disposable

Fig.17:Consumer electronics

10.1:Industrial

1. Direct wireless power and

communication interconnections

across rotating and moving “joints”

(robots, packaging machinery,

assembly machinery, machine tools)

… eliminating costly and failure-prone

wiring.

2. Direct wireless power and

communication interconnections at

points of use in harsh environments

(drilling, mining, underwater, etc.) …

where it is impractical or impossible

to run wires.

3. Direct wireless power for wireless

sensors and actuators, eliminating the

need for expensive power wiring or

battery replacement and disposal.

4. Automatic wireless charging for

mobile robots, automatic guided

vehicles, cordless tools and

instruments…eliminating complex

15

docking mechanisms, and labor

intensive manual recharging and

battery replacement.

Fig.18:Industrial things

10.2:Transportation

Automatic wireless charging forexisting

electric vehicle classes: golf carts, industrial

vehicles.

1. Automatic wireless charging for

future hybrid and all-electric

passenger and commercial vehicles,

at home, in parking garages, at fleet

depots, and at remote kiosks.

2. Direct wireless power

interconnections to replace costly

vehicle wiring harnesses and slip

rings.

Fig.19:Electrical vehicals

10.3:Other Applications

Direct wireless power

interconnections and automatic

wireless charging for implantable

medical devices (ventricular assist

devices, pacemaker, defibrilator,

etc.).

Automatic wireless charging and for

high tech military systems (battery

powered mobile devices, covert

sensors, unmanned mobile robots

and aircraft, etc.).

Direct wireless powering and

automatic wireless charging of smart

cards.

Direct wireless powering and

automatic wireless charging of

consumer appliances, mobile robots,

etc

Fig.20:Other applications

11:ADVANTAGES OF WITRICITY

16

1. No need of line of sight - In witricity

power transmission there is any ;

need of line of sight between transmitter and

receiver. That is power !

transmission can be possible if there is any

obstructions like wood,

metal, or other devices were placed in

between the transmitter and

receiver.

2. No need of power cables and batteries -

Witricity replaces the use of power cables

and batteries.

3. Does not interfere with radio waves

4. Wastage of power is small -

Electromagnetic waves would tunnel, they

would not propagate through air to be

absorbed or dissipated. So the

wastage is small.

5. Negative heaiih implications - By the use

of resonant coupling wave

lengths produced are far lower and thus

make it harmless.

6. Highly efficient than electromagnetic

induction - Electro magnetic induction

system can be used for wireless energy

transfer only if the primary and secondary

are in very close proximity. Resonant

induction system is one million times as

efficient as electro magnetic induction

system.

7. Less costly - The components of

transmitter and receivers are cheaper. So this

system is less costly.

12:DISADVANTAGES

1. Wireless power transmission can be

possible only in few meters.

2. Efficiency is only about 40%.

As witricity is in development stage, lot of

work is done for improving the efficiency

and distance between transmitter and

receiver.

13:COCLUSION:

Witricity is in development stage, lots of

work is to be done to use it for wireless

power applications. Currently the project is

looking for power transmission in the range

of 100w. Before the establishment of this

technology the detailed study must be done

to check whether it cause any harm on any

living beings.

14:Future of witricity

Modern science has now made it possible to

use electricity without having to plug in any

wires. This concept is called witricty which

seems to have a bright future in providing

wireless electricity.

Researchers developed witricity using

resonance where energy is transmitted

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between two copper coils that resonate at the

same frequency. Of these two coils, one is

the power transmitter and the other, the

receiver. The advantage of witricity is that

there is no need of having a line of sight. As

long as the object to be powered has a

source of wireless power, in its vicinity, the

appliacnce charges automatically without

having to be plugged in.

Just imagine the future, with witricity, where

there will be no need of power cables and

batteries. The city just has to be covered

with witricity hot spots wherein you can use

your electric gadget battery and wire free

making it more convenient to carry around

and much lighter. With witricity, there will

be no need of charging batteries, or buying

new batteries for your electrical gadgets.

Just as beneficial witricity may be, there are

some contraindications to the concept, with

debates if it is risky living next to power

lines and having a low power witricity

network running in the home. They wonder

what happens if a glass of water is spilt in a

witricity room. However despite these

contraindications, witricity has a bright

future with the many advantages it provides

in terms of weight, convenience and

portability of electrical appliances.

REFERENCES

1.SasthraKeralammagazine

2.Witricitypower.com

.http://en.wikipedia.org

4.TreeHugger.com

5. http://www.howstuffworks.com

6.A radio transmitter can produce waves having a power of several kilowatts or even megawatts but this energy scatters in all directions. Only a small fraction, less than a millionth part, of the transmitted energy is received. However, this is sufficient to yield the intelligence.

7.^ Jump up to: a b G. A. Landis, "Applications for Space Power by Laser Transmission," SPIE Optics, Electro-optics & Laser Conference, Los Angeles CA, 24–28 January 1994; Laser Power Beaming, SPIE Proceedings Vol. 2121, 252–255.

8. ^ Jump up to: a b Corum, K. L. and J. F. Corum, "Nikola Tesla and the Diameter of the Earth: A Discussion of One of the Many Modes of Operation of the Wardenclyffe Tower," 1996

9.^ Jump up to: a b c d e f General Electric review, Volume 15 By General Electric. "Velocity of Propagation of Electric Field", Charles Proteus Steinmetz

10.Jump up ̂ 188,000 miles per second

11.Jump up ̂ Such as an internal change of load, starting and switching operations, and short circuits.

12.Jump up ̂ Such as the external change due to lightning.

13.Jump up ̂ Charles Steinmetz (Fellow, A. I. E. E. Chief Consulting Engineer, General Electric Company, Schenectady, N. Y.). "Condenser

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Discharge Through a General Gas Circuit". American Institute of Electrical Engineers., 1922. Transactions of the American Institute of Electrical Engineers. New York: American Institute of Electrical Engineers. Presented at the 10th Midwinter Convention of the A. I. E. E., New York, N. Y., 15–17 February 1922.

11. Jump up ̂ viz., the dissipation of electric energy by the resistance of the conductor through its conversion into heat;

12. Jump up ̂ Such as when it gives trouble by induction in telephone circuits or when it reaches such high intensities as to puncture insulation, cause mechanical motion, etc.

13. Jump up ̂ such as an iron needle.

14. ^ Jump up to: a b c Theory and calculation of transient electric phenomena and oscillations By Charles Proteus Steinmetz

15.Jump up ̂ Speculation was made as to what

the electric wave was, leading to the

contradictory deductions that for certain

reasons space is considered as a gas of infinitely

low density, and for certain others as a solid.

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