Transcript 13709798339011_Presentation

Welcome
to
Our
presentation Session
Presentation on
Ohm’s Law, Coulomb’s
Low, Electric Power
& Generators
Continued
Presented By
Name
ID
Intake
Section
Ali Imam
09101101122
20th
4
09101101134
20th
4
Shujauddin
09101101139
20th
4
MD: Zuel
09101101140
20th
4
MD: Shariful ISLAM
Ohm’s Law
Definition
Ohm’s law state that, temperature
remaining constant, the current
passing through a conductor directly
proportional to the potential difference
or voltage across it. This means IαV
OHM'S LAW
I = V/R,
I = current, V = voltage, and R =
resistance
*Depending on what you are trying to
solve we can rearrange it two other
ways.
V=IxR
R = V/I
*All of these variations of Ohm’s Law are
mathematically equal to one another.
History
George Simon Ohm
1826 George Simon Ohm (17871854) wanted to measure the motive
force of electrical currents. He found
that some conductors worked better
than others and quantified the
differences. He waited quite some
time to announce "Ohm's Law"
because his theory was not accepted
by his peers. The unit for resistance is
named after him.
Relationship between P,E,I &R
Ohm's Law defines the relationships between
(P) power, (E) voltage, (I) current, and (R)
resistance. One ohm is the resistance value
through which one volt will maintain a current
of one ampere.
Relationship between P,E,I &R
( I ) Current is what flows on a wire or conductor like water flowing
down a river. Current flows from negative to positive on the surface of a
conductor. Current is measured in (A) amperes or amps.
( E ) Voltage is the difference in electrical potential between two points
in a circuit. It's the push or pressure behind current flow through a
circuit, and is measured in (V) volts.
( R ) Resistance determines how much current will flow through a
component. Resistors are used to control voltage and current levels. A
very high resistance allows a small amount of current to flow. A very low
resistance allows a large amount of current to flow. Resistance is
measured in ohms.
( P ) Power is the amount of current times the voltage level at a given
point measured in wattage or watts.
Coulomb's Law
Definition
Two point charges attract or repel each other
by a force, which is directly proportional to the
product of the magnitude of their charges &
inversely proportional to the square of distance
between them.
The direction of the force depends on the
electrical sign of the charge.
Coulomb's Law
If two point charges Q1 & Q2are separated in a medium by
a distance d, then the electrostatic force F between this
two charges is given by:FαQ1*Q2
Fα1/d2
So, combining the above two equation we can write
FαQ1*Q2/d2 or
F=k Q1*Q2/d2
Here, K is the proportional constant.
The value of K is depends on the system of unit.
In SI system the unit of F is Newton, unit of charge is
coulomb & unit of distance is meter. In this system the
unit of K in free space is,
K=1/4лє0=9*109 Nm2c2
Using Coulomb’s Law
1. Coulomb’s Law applies only to point charges.
(This is particularly important because charge
tends to move around on conductors.)
2. Strictly speaking, Coulomb’s Law applies
only to electrostatics (non-moving charges).
(However, it is usually OK provided v<c).
3. Electrostatic forces, like other forces, can be
superimposed.
Definition
Electric power is the product of electric current and
voltage. It is defined as the rate at which electrical energy
is transferred by an electric circuit
Continued.......
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The electric power in watts associated with a complete
electric circuit or a circuit component represents the rate
at which energy is converted from the electrical energy
of the moving charges to some other form, e.g., heat,
mechanical energy, or energy stored in electric fields or
magnetic fields. For a resistor in a D C Circuit the power
is given by the product of applied voltage and the
electric current
P = VI
Power = Voltage x Current
P=power in watt
T=time in hour
The SI unit of power is watt.
How electric power work
When electric current flows in a circuit, it can
transfer energy to do mechanical or
thermodynamic work. Devices convert electrical
energy into many useful forms, such as heat
(electric heaters), light (light bulbs), motion
(electric motors), sound (loudspeaker) or chemical
changes. Electricity can be produced mechanically
by generation, or chemically, or by direct
conversion from light in photovoltaic cells, also it
can be stored chemically in batteries.
Generators
Definition
Basically speaking, a generator is a device which uses a
magnet in order to induce a flow of electric current in a
circuit, much like how a water pump pushes water
through a hose. A electrical generator is a device that
convents mechanical energy to electrical energy,
generally using electromagnetic induction.
How generator work
A generator functions because of the relation between
magnetism and electricity. If electrons (the parts of an atom
which carry a negative charge) move through something
conductive like a wire, they generate a magnetic field.
Conversely, if a magnetic field is placed near a wire and moved,
its motion causes the electrons in the wire to move because of a
change in electrical potential. This is known as a current.
History
In the 1830s, Michael Faraday discovered this principle
and built the first electromagnetic generator known as the
Faraday disc, which used a copper disc rotating between
the poles of a horseshoe magnet. In 1832, the first
dynamo was built consisting of a power-producing
armature moving within a stationary magnetic field.
Importance
Today, we are very dependent on a steady power supply. The
use of electrical devices like refrigerators and computers
means we can't go without power for very long or there will
be serious consequences. Even so, power outages still occur.
The one the US experienced in 2003 affected over 60 million
people and was the largest outage to occur in US history.
California recently experienced a wave of rolling blackouts. A
New Orleans without power descended in chaos in the wake
of Hurricane Katrina.
Types of Generators
Generators types describes into two ways
Based on output current
Based on structure
Based on output current
AC Generators
DC Generators
AC Generators
This type of generators generates in alternatives current that means the
direction of current changes with time & the shape of current flow the
sign wave.
DC Generators
This type of generators generates in direct current that means the
direction of current is not changes with time & the shape of current flow
the unidirectional wave like a line.
Based on structure
Standby generators
Portable generators
Commercial generators
Based on structure
Standby generators
These are large, often permanent units
that are stationed outside a home,
office building, warehouse, shopping
mall, and the like to provide backup
power in case the mains electricity
switches off. These sets are plugged
into the main electric lines and can
sense when a power interruption has
occurred. They automatically start and
provide emergency power generating a
few seconds after coming online.
Based on structure
Portable generators
These are designed to be transported
whether on a cart, trailer or by hand to
provide power where there is no utility
power supply, as in campsites and
construction sites. Their output is
sufficient to run appliances such as pumps,
refrigerators, lights, radios, and televisions,
and the larger ones can be used to power
sound systems, high-intensity lights and
parked aircraft. The smaller generators
typically use gasoline as fuel, whereas the
larger ones, capable of providing up to
1,000 kilowatts or more of electricity
Based on structure
Commercial generators
In areas where the power supply is
intermittent or lacking as in Third
World provincial areas, generators
can also be set up to provide
additional power.
Is there any question?
Thank You All