1. Electricity… prior to 18th-century people experienced static electricity and naturally occurring electricity (lightening) but didn’t understand it.
In 1663 a device similar to the Van de Graph generator seen in lab was created.

2. Magnetism… was used in the 12th century when it was discovered that an iron-rich magnetic material would align itself with Polaris (the north star). This mineral, magnetite, was the first compass.

3. The Chinese used a compass around 200 B
The Chinese used a compass around 200 B.C to align buildings for best harmony.
The Chinese are considered the first people to use the compass for navigation in the East and the Venetians were the first to use it in the West.

4. Electricity
Non-static electricity is the movement of negatively charged particles
Electrons are negatively charged particles
Unlike charges attract, like charges repel

5. Electrons orbiting an atom’s nucleus:
Metals have lots of extra electrons roaming about, so metals are good conductors of electricity.

6. Electrons want to jump in holes
Electrons orbit the nucleus of atoms
Each electron has a charge of -1
Holes are where electrons are needed to fill electron shells

7. What is a electrical conductor?
A material that allows electrons to flow freely. Most metals are good electrical conductors. Outer electrons are loosely bound to the metal atoms, therefore they can roam freely.
A material that strongly resists the flow of electrons is an insulator. Most non-metals are good insulators.

8. Static Charge
When a bunch of negative particles are separated from positive particles (holes), an electrostatic force is created.

9. Electrical forces are much greater than gravitational forces
Electrical forces are much greater than gravitational forces. Gravity is always an attractive force, but electrical forces can be both attractive or repulsive.

10. Electrostatic forces can be stronger than the force of gravity.

11. Xerographic Copies use electrostatic charge to produce & transfer images
Photoconductor only conducts charge when exposed to light.
A document image is projected onto a rotating photoconductor drum. An image identical to the original black and white is produced with charged particles. The portions that remain charged are the ‘black’.
Oppositely charged toner adheres to the charged portion of the photoconductor.
A charged piece of paper makes contact with the photoconductor and the toner image is transferred to the paper.
The paper is then heated and the toner is fused onto the paper.

12. Chester Carlson Physicist, Engineer, & Patent Lawyer
Develops the electrophotography process in 1938
Acquires patents for the process
Seeks investors from IBM, RCA, General Electric, and the US Army
Finally in 1944 convinces Haloid Co. that idea has commercial viability.
Process is coined XeroX, and Haloid Co. changes its name to Xerox and begins selling copiers in 1950
Plain Paper copies come out in 1959; sales surge along with Xerox’s revenue

13. Photocopier Process http://www.howstuffworks.com/photocopier1.htm
Photocopier Drums are light sensitive.
They are made of semiconductor materials.
This photoconductive material becomes conductive when in light, but not conductive in the dark.
Charge can leave the drum where light hits the drum. Charge remains in the areas where light did not shine.

14. Leyden Jar
In 1746 two scientists in Holland experimented with a device that could store charge/electrons. This was the first “capacitor”.
By touching the knob with a
charged rod, more and more
charge could be stored in the
Leyden Jar.
Homemade jar with tin foil.
Wikipedia

15. Ben Franklin’s Kite Experiment
Ben Franklin thought the sparks from static electricity looked a lot like lightning.
A wire was attached to the kite’s
string with a key at the end. The key
was attached to a Leyden Jar via a
Small wire.
It is unlikely Franklin ever did the
legendary experiment because
two people who tried this
experiment died.
The installation of Lightening Rods
to protect tall buildings came
from Franklin.

16. Van De Graph Generator produces static charge

17. Franklin’s Static Electric Motor
Electrons hitch-hike on the thimbles to neutralize the + side, thus making the rotor spin around.

18. What is electric current? I = charge/time
The Physics
Classroom
Negatively charged particles called electrons are moving through conductors such as wires.
If the electrons flow at a constant rate and always flow in the same direction, we say it is DC (direct current).
If the electrons periodically change direction, the current is AC (alternating current).

19. Ohm’s Law
V = IR
V – voltage is electrical force that causes electrons to flow
I - Current is the flow rate of electrons
R – Resistance to electron flow

20. Henry Cavendish (recall he discovered the constant G)
In 1781 Cavendish discovers electrical potential across a wire with resistance. He discovers that electric current naturally flows from high to low potential and the higher the potential the more current flows.
Georg Ohm publishes the same result plus a complete theory on electricity in 1827.
Voltage
Current
V = IR

21. Current in the Nichrome wire
Electrical Energy is converted into light and heat by passing current through a resistive wire.

22. Power P = V I (watts = Joules/sec)
Recall James Joule from the famous paddle wheel experiment in the Thermodynamics section.
P = V I (watts = Joules/sec)
P – Power is the rate of work being done
(units are watts, horsepower, etc.)
V – Voltage (volts)
I – Current (amps)
P X time = Energy (KWH, BTU, Joules, Calories)

23. To perform work, a continuous flow of charge is required
Charge is expressed in Coulombs
Current  Coulombs/second
Amp = 1 Coulomb/second
Some kind of device or system was needed to produce a continuous flow of charge.

24. Meanwhile….
Luigi Galvani’s conducts experiments with “animal electricity” using frogs’ legs
Applying static electricity to dissected frogs’ legs caused the legs to twitch. (c )
Galvani later laid frog legs out on brass hooks that were hooked onto an iron lattice during a thunderstorm. The frog legs continued to twitch after the storm.
Alessandro Volta hypothesized that the twitching might be electricity caused by the two different metals (brass and iron).

25. Galvani hanging frog legs on brass hooks. Luigi Galvani
Two metals causing legs
To twitch.
Luigi Galvani

26. Alessandro Volta and the Battery
A battery using copper and zinc, interleaved with cardboard soaked in brine (a good electrical conductor).
Volta presented in 1800 the world’s first device that could
deliver continuous current.
Wikipedia
An accomplishment that took
50 years, lots of experimentation,
and luck too.

27. An electrochemical cell has three main parts: two dissimilar metals and an electrolyte. The electrolyte allows ions and electrons to move between the two metals. By creating a closed path, electrons will flow and electricity can be delivered to a device.

28. The Carbon and Zinc dry-cell battery
First demonstrated in 1866.
This is a chemical reaction where electrons are exchanged between two metals, causing continuous current through a load. This is a form of chemical energy.
Wikipedia

29. Battery Reactions
Sulfuric Acid reacts with Zinc, producing positive zinc ions and electrons.
Attaching a load (motor, light bulb, etc.) between the zinc and the graphite (carbon) allows the electrons to flow to the carbon side where the electrons join with H+ ions.

30. Lead Acid Battery Reactions
Pb + SO4²¯ → PbSO4 + 2e- + H+ The reduction potential of this reaction is Volts.
PbO2 + SO4²¯ + 4 H+ + 2e- → PbSO4 + H2O The potential of this reaction is volts.
Total voltage created is about 2V.
Lead Acid batteries provide high current,
and are rechargeable, making them
effective for starting cars.

31. An auspicious moment in 1820…
Hans Christian Oersted, a Danish Physics professor, was demonstrating electricity when he noticed that whenever the battery was connected such that current flowed in a wire, a nearby compass needle would twitch!!!
Oersted by accident discovered that electricity and magnetism are related.
His experiment showed that current in a wire has a magnetic field around it.

32. Current in wire
Compass

34. Electromagnets in Industrial Applications
istockphoto

35. Michael Faraday
Faraday was a self-taught scientist fascinated with science.
In 1831 he showed the reverse of Oersted’s experiment: That electricity is created in a wire when the wire is moved through a magnetic field. This is called
Electromagnetic Induction

37. Faraday’s Generator
Faraday demonstrated that rotational energy could be converted into electrical energy.
This was the first generator.
It delivered continuous
current.

38. Faraday demonstrates the Transformer
Two coils very close together.
Current in the first coil, sets up a magnetic field. This magnetic field induces current in the second coil.
The transformer allows the stepping up or down of current based on the ratio of windings in the first coil to the second coil.
If current goes up, voltage steps down. If current steps down, voltage steps up.
Wikipedia

39. Steam Powered Generators
By the 1850’s coal was burned to make steam which in turn was used to turn a generator to produce continuous current.
Electricity meant instant, on demand clean power (never mind the coal burning in the next building).

41. Thomas Edison was determined to provide electricity to light homes.
Edison was convinced that electricity should be DC (direct current).
DC voltage can not be easily stepped up to high voltages/low current, therefore it was impractical for supplying electricity over long distances.

42. DC makes an attempt…
In the 1880’s there were a few DC power stations in England

43. Nikola Tesla invented the Generator/Dynamo in 1880’s
Current alternates

44. AC wins by the 1890’s
AC power stations that generate power at 10,000 volts are built. The voltage is stepped down using transformers.
This is similar to today’s technology.
Oregon Historical Society

45. Power Grid is based on AC voltage This allows stepping up and stepping down of voltage using transformers.

46. Maxwell’s Equations
James Clerk Maxwell took Faraday’s discoveries and put them into equations. The four equations state:
1. Like charges repel, unlike charges attract
2. Magnetic fields always have two poles (positive and
negative)
3. A moving/changing magnetic field can produce current.
4. Moving electrical charge (current) can produce a
magnetic field.

47. From the Generator we get the Motor
The current direction in the wires changes with every half rotation. This electromagnetic has a constantly changing magnetic field, causing the coil to continue to realign inside with the permanent magnet (the stator). This makes the rotor spin.
Wikipedia

48. Maxwell predicts Electromagnetic Radiation
An electromagnetic wave exists when the changing magnetic field causes an electric field which then causes another changing magnetic field, and so on forever.
These oscillating fields together form an electromagnetic wave.
An electromagnetic wave will travel and continue on forever until absorbed.
Wikipedia.com

49. Heinrich Hertz demonstrates in 1888 the existence of electromagnetic radiation

50. Physical Contact does not need to be made to measure electric or magnetic fields.
An electric field exerts a force on charged objects.
A magnetic field exerts a force on moving charge.
All the magnetic fields we experience are the result of moving charges.
Electromagnets make magnetic fields with current in wires. Permanent magnets produce magnetic fields through the orientation of the electron orbits and spins of the atoms in the magnet. Arthur Smith

51. Magnets
Since paired electrons spin in opposite directions, their magnetic fields cancel one another out. Atoms of ferromagnetic elements, on the other hand, have several unpaired electrons that have the same spin. Iron, for example, has four unpaired electrons with the same spin. Because they have no opposing fields to cancel their effects, these electrons have an orbital magnetic moment.
Iron and other ferromagnetic materials are crystalline. As they cool from a molten state, groups of atoms with parallel orbital spin line up within the crystal structure, forming a permanent magnet.
Magnets attract materials that have unpaired electrons.
Howstuffworks

52. A non-turbine Generator (Micro Wind Generator)
And where did this idea come from?

53. Text Sources
The Sciences- 5e, Trefil and Hazen
A History of Great Inventions, James Dyson
Internet