Unification of the Electricites

1
Unification of the Electricites

• Faradays Research Resulting in the Unification
  of the Five Kinds of Electricity

2
Unifications

• There have been several important Unifications in
  Physics
• Unification of Electricities
• Unification of Electricity and Magnetism
• Special Relativity
• Unification of EM and Quantum Mechanics
• Unification of EM and Weak Force
• Yet to come
• Unification of Gravity and Quantum Mechanics

3
What is so Special about Unification?

• Is it nothing more than being able to write down
  a theory in one equation instead of two?
• Each Unification brought with it a surprise, a
  new understanding, and new phenomenon
• Putting the pieces of a puzzle together revealed
  missing pieces

4
Unification of Electricities

• Paper published by Michael Faraday in 1832
  unified the five kinds of electricities
• Voltaic Electricity
• Ordinary Electricity
• Magneto-Electricity
• Thermo-Electricity
• Animal Electricity

5
Michael Faraday

• Born 1791 in London
• Apprenticed as a Book Binder at age 14 in 1805
• In 1813 took position as Humphrey Davys
  assistant
• 1814 to 1815 Continental tour
• 1821 Invents continuous rotation
• 1832 Paper on Electricities
• Died in 1867

6
Route taken by Davy and Faraday on the
Continental tour 1814 to 1815. In Paris Davy
discovered Iodine in Amperes laboratory. They
experimented with electric fish in Genoa. In
Florence they burned a diamond and determined it
was made of carbon.
7
Faradays Laboratory at the Royal Institution
8
Table of Experimental Effects

• The five electricities should all exhibit the
  same effects
• The Xs are effects Faraday saw, s were
  observed by others

9
Voltaic Electricity

• Voltaic electricity is from common batteries.
• Each cell in a battery has fixed voltage
  determined by the chemical reaction typically
  about 1.5 volts
• Higher voltage is made by stacking several cells

10
The Great Battery at the Royal Institution
11
Ordinary Electricity

• Ordinary Electricity is also commonly called
  static electricity or tribo-electricity
• When different materials are rubbed together
  electrons will be transferred from one to the
  other

12
Magneto-Electricity

• When a magnet is moving through a coil a voltage
  is induced at the ends of the coil
• This is known as Faraday Induction and is the key
  principle for the operation of all motors and
  generators

13
Thermo-Electricity

• Discovered by Thomas Seebeck in 1821
• Two dissimilar metals are connected together
• One junction is heated, the other cooled
• Current will flow around the loop

14
Animal Electricity
15
Table of Experimental Effects

• The five electricities should all exhibit the
  same effects
• The Xs are effects Faraday saw, s were
  observed by others

16
Voltage and Current

• The ideas of Voltage and Current had not been
  fully developed.
• Faraday referred to
• Electricity of Tension
• Electricity of Motion
• This distinction he calls merely convenient and
  not as philosophical
• Amperes theory of current was electricity
  consisted of two kinds of fluid, and a current
  was the flow of the two fluids simultaneously in
  opposite directions

17
Physiological Effects

• The power of the voltaic current, when strong,
  to shock and convulse the whole animal system,
  and when weak to affect the tongue and the eyes,
  is very characteristic.
• A frog was convulsed in the earliest experiments
  on these magneto-electricity currents. The
  sensation upon the tongue, and the flash before
  the eyes, which I at first obtained only in a
  feeble degree, have been since exalted by more
  powerful apparatus, so as to become even
  disagreeable.

18
Magnetic Deflection

• No fact is better know to philosophers than the
  power of the voltaic current to deflect the
  magnetic needle, and to make magnets according to
  certain laws and no effect can be more
  distinctive of an electrical current.

19
Spark

• The beautiful flash of light attending the
  discharge of common electricity is well known.
  It rivals in brilliancy, if it does not even very
  much surpass, the light from the discharge of
  voltaic electricity but it endures for an
  instant only, and is attended by a sharp noise
  like that of a small explosion.

20
Heating Power

• The heating power of common electricity, when
  passed through wires or other substances, is
  perfectly well known. The accordance between it
  and voltaic electricity is in this respect
  complete.

21
True Chemical Action

• I do not intend to deny that with such an
  apparatus common electricity can decompose water
  in a manner analogous to that of the voltaic
  pile But the quantities were so small, that on
  working the machine for half an hour I could not
  obtain at either pole a bubble of gas larger than
  a small grain of sand.

22
Attraction and Repulsion

• The attractions and repulsions due to the
  tension of ordinary electricity have been well
  observed with that evolved by magneto-electric
  induction. M. Pixii, by using and apparatus,
  clever in its construction and powerful in its
  action, was able to obtain great divergence of
  the gold leaves of an electrometer.

23
Discharge by Hot Air

• As heated air discharges common electricity with
  far greater facility than point, I hoped that
  voltaic electricity might in this way be
  discharged.

Whilst in the state described, no decomposition
took place at the point a, but when the side of a
spirit-lamp flame was applied to the two platina
extremities at e, so as to make the bright
red-hot, decomposition occurred.
24
Faradays Conclusion

• The general conclusion which must, I think, be
  drawn from this collection of facts is, that
  electricity, whatever may be its source, is
  identical in its nature. The phenomena in the
  five kinds of species quoted, differ, not in
  their character but only in degree and in that
  respect vary in proportion to the variable
  circumstances of quantity and intensity which can
  at pleasure be made to change in almost any one
  of the kinds of electricity, as much as it does
  between one kind an another.

25
Conclusion

• This is the first of the Unifications, Faraday
  had amply demonstrated the unity of electricities
• But a full theoretical understanding of the
  experiments was lacking
• The next step toward a theory was the field
  concept, again initiated by Faraday, which we
  will take up next meeting.