1. The document discusses wireless electricity or "witricity", which is the transfer of electric power over distance without wires. It can be done using coupled magnetic resonators to efficiently transfer power in non-radiating fields. 2. Witricity allows devices to be charged without plugging in, and could eliminate the need to replace batteries. Power is transmitted from a charging coil through an inductive magnetic field to a receiving coil. 3. For efficient wireless power transfer, the transmitting and receiving coils must be in "strongly coupled" magnetic resonance. This allows energy to be exchanged efficiently even over some distance between the coils.

1. WIRELESS ELECTRICITY(WITRICITY)
M Ayesha Mubeen
Final Year B.Tech, Dept. of ECE
Shadan Women’s College of Engineering and Technology
ayeshamubeen04@yahoo.com
Abstract- Can we imagine the life without
electrical wires? From now answer to this question is
yes. The method proposed in the present paper called
“Witricity” will facilitate to Transfer power without
using wires. The efficient midrange power can be
transmitted to any device which uses that range of
power by the technique used in this Witricity concept.
Now a days there is a Rapid development of
autonomous electronics like Laptops, Cell-phones,
House -hold robots and all the above devices
typically rely on chemical energy storage(Battery)
.As they are becoming daily needs to present
generation, Wireless energy transfer would be useful
for many applications as above and they need
midrange energy. This is the main reason to prepare
this paper. Wireless electricity or witricity is the
transfer of electric energy or power over a distance
without the use of wires. In order for the energy to be
transferred safely coupled resonators are used. When
two magnetically resonating objects at “Strongly
coupled” regime tend to exchange energy efficiently
by transfer of power in the non-radiating fields. This
is the basic principle involved in it. By taking two
coils having same magnetic resonance and one is
coupled to source and other is coupled to Device. So
that the energy transfer is efficient even the air gap
between them is high. This paper describes the basic
history of wireless power transmission, what are
Magnetic resonance and strongly coupled regime,
Experimental design, Range and rate of coupling
(coupling calculations) and Design of parameters and
Simulation for variation of power with and without
the external object between source and load. Using
witricity there would be no need to replace batteries
because energy could be transferred from one sensor
to another.
Keywords- Witricity, Electrical resonance,
electromagnetic induction, charging algorithm, power
capturing device.
I. INTRODUCTION
Wireless electricity or witricity is the transfer of
electric energy or power over a distance without the
use of wires. In our present electricity generation
system we waste more than half of its resources.
Especially the transmission and distribution losses are
the main concern of the present power technology.
Much of this power is wasted during transmission
from power plant generators to the consumer. The
resistance of the wire used in the electrical grid
distribution system causes a loss of 26-30% of the
energy generated. This loss implies that our present
system of electrical distribution is only 70-74%
efficient. We have to think of alternate state - of - art
technology to transmit and distribute the electricity.
Now- a- days global scenario has been changed a lot
and there are tremendous development in every field.
If we don’t keep pace with the development of new
power technology we have to face a decreasing trend
in the development of power sector. The transmission
of power without wires may be one noble alternative
for electricity transmission.
II. ORIGINATION
Wireless power transmission is not a new idea.
Nickolas Tesla demonstrated transmission of
electrical energy without wires in early 19th century.
Tesla used electromagnetic induction systems.
William C Brown demonstrated a micro wave
powered model helicopter in 1964. This receives all
the power needed for flight from a micro wave beam.
In 1975 Bill Brown transmitted 30kW power over a
distance of 1 mile at 84% efficiency without using
cables. Researchers developed several technique for
moving electricity over long distance without wires.
Some exist only as theories or prototypes,but others
are already in use.Consider an example, in this
electric devices recharging without any plug-in. The
device which can be recharged is placed on a charger.
Supply is given to the charger and there is no
electrical contact between charger and device. The
recharging takes place in following steps.
1. Current from the wall outlet flows through a coil
inside the charger, creating a magnetic field. In a
transformer, this coil is called the primary winding.
2. When the device placed on the charger, the
magnetic field induces a current in another coil, or
secondary winding, which connects to the battery.
3. This current recharges the battery.
Fig. Shows chargingof battery

2. III. PRINCIPLE OF WITRICITY
It revels the main idea of the “resonance
condition” between two circuits”. A. Electrical
resonance: - Electrical resonance occurs in an electric
circuit at a particular resonance frequency when the
impedance between the input and output of the circuit
is at a minimum (or when the transfer function is at a
maximum). Often this happens when the impedance
between the input and output of the circuit is almost
zero and when the transfer function is close to one.
Resonance of a circuit involving capacitors and
inductors occurs because the collapsing magnetic
field of the inductor generates an electric current in its
windings that charges the capacitor, and then the
discharging capacitor provides an electric current that
builds the magnetic field in the inductor, and the
process is repeated continually. Formula of resonance
frequency:
where ω = 2πf, in which f is the resonance frequency
in hertz, L is the inductance in henries, and C is the
capacitance in farads when standard SI units are used.
Many sounds we hear, such as when hard objects of
metal, glass, or wood are struck, are caused by brief
resonant vibrations in the object. Light and other short
wavelength electromagnetic radiation is produced by
resonance on an atomic scale, such as electrons in
atoms.
IV.METHOD FOR WIRELESS
POWER TRANSMISSION
The method used for wireless power transfer
is the electrical is the electrical transformer. In this
the electrically isolated from each other. The transfer
of energy takes place by electromagnetic coupling
through mutual induction. The main drawback of this
method is the short range. For efficient working of a
system, which uses this method, the receiver must be
in very close proximity to the-transmitter. A larger,
stronger field can be used for energy transfer over
large distance, but this process is extremely
inefficient. Since magnetic field spreads in all
direction, making a large wastage of energy. Pushing
a person in a swing is a common example of
resonance. The loaded swing, a pendulum, has a
natural frequency of oscillation, its resonant
frequency, and resists being pushed at a faster or
slower rate. One familiar example is a playground
swing, which acts as a pendulum. Pushing a person in
a swing in time with the natural interval of the swing
(its resonance frequency) will make the swing go
higher and higher (maximum amplitude), while
attempts to push the swing at a faster or slower tempo
will result in smaller arcs. This is because the energy
the swing absorbs is maximized when the pushes are
'in phase'with the swing's oscillations, while some of
the swing's energy is actually extracted by the
opposing force of the pushes when they are not.
Resonance occurs widely in nature, and is exploited
in many man-made devices. It is the mechanism by
which virtually all sinusoidal waves and vibrations
are generated.
4.2. CONDITIONS FOR WITRICITY
CHARGING
The first condition necessary is that charging
must be able to occur through physical objects. If the
witricity cannot be passed through physical objects
then the charging can only occur in a perfect
unobstructed environment. This is not realistic
because there are objects all around us that can
interfere with the transmission of the energy.
Research thus far has found that witricity can be
transmitted through wood, gypsum wallboard,
plastics, textiles, glass, brick, and concrete.
The second condition necessary is that charging
must be safe and not pose any sort of threat or safety
hazard to humans or animals. Since this type of
energy transfer is non-radioactive it is safe for
humans and animals.
The third condition necessary is that witricity
charging must be able to provide electricity to remote
objects without the use of wires. Therefore, the
energy must be transferable from the transmitter to
the capturing device over a certain distance.
The fourth condition necessary is that the
witricity is able to transfer a meaningful amount of
energy, or else it would defeat the purpose of the
energy transfer.
4.3. PARAMETERS
The first parameter is the degree of charging.
There are three different degrees in which a sensor
can be charged. The first is perfect charging, this type
of charging charges all the batteries of the sensors
until they are all full.

3. This is achieved by using an external power
source such as a base station or using designated
power supply devices. The second way is limited
charging, this type of charging charges the batteries
of the sensors that are at or above a certain threshold.
It could have an external power source, but if it does
not it will try to maximize the network lifetime
without creating a blind spot in the wireless sensor
network.
The second parameter is the type of charging
algorithm. There are two different charging
algorithms; distributed and centralized. The
distributed algorithm calculates the amount of energy
that needs to be transferred between a node and its
direct neighbor based on information received from
its direct neighbor. The centralized algorithm
calculates the amount of energy that needs to be
transferred between all the sensors in the network.
The third parameter is the type of power supply.
There is a base station and either all of the sensors or
some of the sensors are indicated as a percentage
between 0 and 100%. It also allows the base station to
select a set of certain sensors. There are also
designated power supply devices that are non-sensor
power supply devices that are deployed in the WSN.
The fourth parameter is the type of power
capturing device. There is a base station and the
sensors are indicated as percentages too, the
difference is the devices and base station might be a
power capturing device or act as an intermediate
power relay device.
V. HOW WOULD BE THE FUTURE WITH
WITRICITY
Modern science has now made it possible to
use electricity without having to plug in any wires.
This concept is called witricity which seems to have a
bright future in providing wireless electricity.
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,lot
of work is to be done in improving the range of power
transmission and efficiency.
VI. ADVANTAGES
-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 are any
obstructions like wood, metal, or other devices were
placed in between the transmitter and receiver.
-No need of power cables and batteries -
Witricity replaces the use of power cables and
batteries.
-Does not interfere with radio waves.
-Does not interfere with radio waves.
-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.
-Highly efficient than electromagnetic induction
- Electromagnetic 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
electromagnetic induction system.
-Less costly, the components of transmitter and
receivers are cheaper. So this systemis less costly.
VII. APPLICATIONS
Witricity has a bright future in providing
wireless electricity. There are no limitations in
Witricity power applications. Some of the potential
applications are powering of cell phones, laptops and
other devices that normally run with the help of
batteries or plugging in wires. Witricity applications
are expected to work on the gadgets that are in close
proximity to a source of wireless 'power, where in the
gadgets charges automatically without necessarily,
having to get plugged in. By the use of witricity there
is no need of batteries or remembering to recharge
batteries periodically. If a source is placed in each
room to provide power supply to the whole house.
Witricity has many medical applications. It is used for
providing electric power in many commercially
available medical implantable devices. Another
application of this technology includes transmission
of information. It would not interfere with radio
waves and it is cheap and efficient.
VIII.CONCLUSION
The transmission of power without wires is
not a theory or a mere possibility, it is now a reality.
The electrical energy can be economically transmitted
without wires to any terrestrial distance.