Transcript nature phenomenon of electricity and magnetism

History of Electricity and Magnetism
Pioneers in discovering electricity
1752- Benjamin Franklin was the first to discover electricity with
his famous kite flying experiments.
1800- Alessandro Volta made a miraculous discovery. By
stringing these electrical cells together he was able to create
a battery. In his honor battery power is measured in volts.
1879- Thomas Edison experimented by soaking cotton thread in
carbon and used a small wire, known as a filament to conduct
electricity.
Concepts
Charge Conservation: No matter how the charges are rearranged the total amount
of charge within any closed system is constant. q e = -1.6 x 1019C
Coulombs Law: F=Kq1q2 / R2 where K =9 x 109
Nm2/C2
Charging By Induction：A charged object brought near to a conducting uncharged
object will induce electrons to move on the surface of the conductor.
Electric Field Strength: E = F/q2 = kq1/R2 (where the direction of E is the same as
the direction of the force on a positive test charge )
Electric Dipole: Positive Electric Charges naturally would move away from the
positive charge and toward the negative charge.
volt is a measure of potential difference: V = W/q = Fd/q = Ed
Concepts cont.
Current –
I = V/R rate of flow of charge 1 Ampere (I) = 1 coulomb/sec
Parallel Circuits Resistors connected in parallel provide more than one path
through which charge can flow.
IT = I1+ I2 V/RT = V/R1 + V/R2 1/RT = 1/R1 + 1/R2
Combination Circuits: Voltage drops around any one closed loop = voltage
rises given by supply. RT = R1 + R2
Electric Transformers: Power In= Power Out
Transformer Equation: (Vs/ Vp) = (Ns / Np)
Vs Is = Vp Ip
Usage of Magnets
At home we use
magnets to hold things
up or to pick up small
things:
• sewing pins
• electric can openers
• hold things to the
refrigerator.
.
Maglev trains
Maglev trains use super conducting magnets in the track
and on the underside of the train to “float” above the track.
Maglev trains can travel very fast, up to 480 km/h (300 mph).
These Maglev trains are being used in Japan. This train line
opened in April 1997. In April of 1999 this train was clocked
at an incredible 343 miles an hour! The United States
government has set aside 1 billion dollars to build a Maglev
train.
An aurora is a natural light
display in the sky, caused by
the collision of charged
particles directed by the
Earth's magnetic field. An
aurora is usually observed at
night and typically occurs in
the ionosphere. These
phenomena are commonly
visible in a ring just within the
Arctic and Antarctic polar
circles.
Lightning is an atmospheric discharge of
electricity accompanied by thunder. In the
atmospheric electrical discharge, a leader of a
bolt of lightning can travel at speeds of
220,000 km/h and can reach temperatures
approaching 30,000 °C.
Impact of Electricity and
Magnetism
Electricity and magnetism
has come a long way since
1752. We use it for just
about everything. From
toasting our bread to
keeping streets safe and
running smoothly. The
discoveries these
scientists made so very
long ago have paved the
way for our productive,
thriving communities
today.
Sources
www.aboutnuclear.org
www.need.org/needpdf//infobook
www.thehistoricalarchive.com