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The Nature of ElectricityPowerPoint Presentation

The Nature of Electricity

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The Nature of Electricity. By Chuck Hobson BA, BSc(hons). INTRODUCTION. This “Nature of Electricity” presentation has been modified to include some of the remarks I usually make as I proceed through the slides. If you have any questions, please email them to me at:. CREDITS.

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INTRODUCTION

This “Nature of Electricity” presentation has been modified to include some of the remarks I usually make as I proceed through the slides.

If you have any questions, please email them to me at:

Georg Simon Ohm 1787 - 1854

Elektrizität! Was ist es?

André Marie Ampère 1775 - 1836

L'électricité! Qu'est-ce que c'est ?

Charles Augustin Coulomb 1736 - 1806

Elettricità! Che cosa è esso?

Count Alessandro Volta 1745 - 1827

Michael Faraday 1791 - 1867

Electricity! What is it?

James Watt 1736-1819

Joseph Henry 1797 – 1878

Nikola Tesla 1856 - 1943

Georg Simon Ohm 1787 - 1854

Elektrizität! Was ist es?

André Marie Ampère 1775 - 1836

L'électricité! Qu'est-ce que c'est ?

Charles Augustin Coulomb 1736 - 1806

Elettricità! Che cosa è esso?

Count Alessandro Volta 1745 - 1827

Michael Faraday 1791 - 1867

Electricity! What is it?

James Watt 1736-1819

Joseph Henry 1797 – 1878

Nikola Tesla 1856 - 1943

Georg Simon Ohm 1787 - 1854

Elektrizität! Was ist es?

André Marie Ampère 1775 - 1836

L'électricité! Qu'est-ce que c'est ?

Charles Augustin Coulomb 1736 - 1806

Elettricità! Che cosa è esso?

Count Alessandro Volta 1745 - 1827

Michael Faraday 1791 - 1867

Electricity! What is it?

James Watt 1736-1819

Joseph Henry 1797 – 1878

Nikola Tesla 1856 - 1943

Georg Simon Ohm 1787 - 1854

Elektrizität! Was ist es?

André Marie Ampère 1775 - 1836

L'électricité! Qu'est-ce que c'est ?

Charles Augustin Coulomb 1736 - 1806

Elettricità! Che cosa è esso?

Count Alessandro Volta 1745 - 1827

Michael Faraday 1791 - 1867

Electricity! What is it?

James Watt 1736-1819

Joseph Henry 1797 – 1878

Nikola Tesla 1856 - 1943

Georg Simon Ohm 1787 - 1854

Elektrizität! Was ist es?

André Marie Ampère 1775 - 1836

L'électricité! Qu'est-ce que c'est ?

Charles Augustin Coulomb 1736 - 1806

Elettricità! Che cosa è esso?

Count Alessandro Volta 1745 - 1827

Michael Faraday 1791 - 1867

Electricity! What is it?

James Watt 1736-1819

Joseph Henry 1797 – 1878

Nikola Tesla 1856 - 1943

Georg Simon Ohm 1787 - 1854

Elektrizität! Was ist es?

André Marie Ampère 1775 - 1836

L'électricité! Qu'est-ce que c'est ?

Charles Augustin Coulomb 1736 - 1806

Elettricità! Che cosa è esso?

Count Alessandro Volta 1745 - 1827

Michael Faraday 1791 - 1867

Electricity! What is it?

James Watt 1736-1819

Joseph Henry 1797 – 1878

Nikola Tesla 1856 - 1943

Note they all have units of electricity named after them.

THE ELECTRON FOUND IN ALL MATTER

HEART OF ELECTRICITY

- SOME PROPERTIES
- Radius < 10-15 metres
- Rest mass 9.1 × 10-28 grams
- Charge neg. 1.6 × 10-19 Coulombs

HOW SMALL? A thousand trillion electrons side by side measure 0.5m

HOW HEAVY? 1.2 thousand trillion trillion electrons weigh one gram

HOW POTENT? 6.25 million trillion electrons make a 1 Coulomb charge

One Coulomb flowing per second = one Ampere.

One gram of electrons contains 176,000,000 Coulombs of charge

PUTTING THE ELECTRON TO WORK

Note: Ideal model used, Wires have zero resistance, light illuminates instantly and resistance is a fixed 100 ohms.

PUTTING THE ELECTRON TO WORK

Note: If an oscilloscope and photo cell at the battery/SW end is triggered at SW closure, the photo cell & oscilloscope would see the light 6.67µs later.

A QUESTION

WHERE DID THE 3.3µs COME FROM?

- 3.3µs was arrived at using a Radar type calculation
- Velocity x time results in distance travelled (v x t = d)
- In Radar v = c, the speed of light- 300 million metres per seconds.
- Radar range (c x t = d) 300 x 106ms-1 x 3.3 x 10-6s = 1000m (one way)
- In our case we know d (1000m) and c, so we calculate t

or 3.3µs

Now consider current flow again

CURRENT FLOW

Current measures 1A in fig 3. What about the current in figures 1 & 2?

CURRENT FLOW

The battery doesn’t see the 100 ohm load in figures 1 & 2 All it sees is the characteristic impedance of the pair of wires In our example, this impedance is assumed to be 400 ohms.

ANOTHER QUESTION

Can electrons travel through wire at the speed of light ( c ) where c = 300,000,000 metres per second?

- No way Jose!
- Why not?

- Reason:
- Electrons are particles with mass as previously stated
- As particles approach c their masses increase enormously
- This is in accordance with Einstein’s “Special Relativity”
- This has been demonstrated at Cern and SLAC
- Cern and SLAC use GeV’s to reach near c velocities
- No particles including the electron have ever been accelerated to c

ELECTRON VELOCITY-1

ELECTRON VELOCITY IN A VACUUM TUBE

ELECTRON VELOCITY-1

ELECTRON VELOCITY IN A VACUUM TUBE

Formula from A-Level Physics

Calculation

v = velocity electron reaches at A anode

= 26.5 million metres per second (final velocity at the anode)

Let’s increase voltage on the Anode of the tube and calc. velocities

ELECTRON VELOCITY-1

SOMETHING WENT WRONG! Electrons CANNOT exceed c!

Increase in mass with velocity (relativistic mass) was not taken into account

ELECTRON VELOCITY-2

When a mass velocity approaches the speed of light its mass increases

This is in accordance with Einstein’s theory “Special Relativity”

That is to say: relativistic mass (mr) = gamma ( ) times mo

Relativistic mass calculations are done using the following formulas:

#1

where

#2

#3

eV = electron volt is a unit of energy used in particle physics

#4

ELECTRON VELOCITY-2

When a mass velocity approaches the speed of light its mass increases

This is in accordance with Einstein’s theory “Special Relativity”

That is to say: relativistic mass (mr) = gamma ( ) times mo

Relativistic mass calculations are done using the following formulas:

#1

where

#2

#3

eV = electron volt is a unit of energy used in particle physics

#4

ELECTRON VELOCITY-2

When a mass velocity approaches the speed of light its mass increases

This is in accordance with Einstein’s theory “Special Relativity”

That is to say: relativistic mass (mr) = gamma ( ) times mo

Relativistic mass calculations are done using the following formulas:

#1

where

#2

Known as the LorentzTransform

#3

eV = electron volt is a unit of energy used in particle physics

#4

ELECTRON VELOCITY-2

When a mass velocity approaches the speed of light its mass increases

This is in accordance with Einstein’s theory “Special Relativity”

That is to say: relativistic mass (mr) = gamma ( ) times mo

Relativistic mass calculations are done using the following formulas:

#1

where

#2

Known as the Lorentz Transform

#3

eV = electron volt is a unit of energy used in particle physics

#4

ELECTRON VELOCITY-2

On the last entry, notice the significant mass increase (x 17,219)

ELECTRON ENERGY VELOCITY CHART

NOTE 299,999,880m/s is just 120m/s short of the speed of light

A QUESTION REVISITED

ELECTRONS DIDN’T TRAVEL AT c BUT THE SOMETHING DID

1. How about the “nudge” theory (cue ball effect etc.)?

Electrons out of the negative terminal nudge the next one on etc. The end result could be electrons at the light bulb 3.3µs later (?)

There have been many arguments on this issue since the 1920’s A paper on this notion was submitted to the 1997 IEE.

RECTANGULAR PULSE

WHAT IS HAPPENING DURING INTERVALS: (A – B), (B – C), (C – D)?

(A – B) and (C – D)? Nothing! There is NO voltage or current B – C? 100V and 0.25A

Note: Z of the transmission line pair = 400 Ohms. What would the situation be in 5.66µs?

RECTANGULAR PULSE

Negative pulse moving back to the Pulse Generator

SINGLE RECTANGULAR PULSE EXAMINATION

RECTANGULAR PULSE Time Domain: Viewed on an Oscilloscope

RECTANGULAR PULSE Frequency Domain: Viewed on a Spectrum Analyser

Pulse reconstruction formula

Fast Fourier Transform formula

RECAP

- The nudge (cue ball) explanation of conduction unresolved
- Electrical energy travels ~ speed of light over wires to a load.
- Likewise, pulses travel ~ the speed of light over wires.
- Single pulses are made up of wide spectrums of frequencies
- Pulse (spectrum of frequencies) travel as TEM signals at ~ c
- In the circuit comprising a 100V battery, switch & light bulb: the leading edge of a pulse occurs at 100V switch on and the trailing edge of a pulse occurs at 100V switch off
- Very long pulses have same properties as very short pulses
- AC signals to µ-wave frequencies) travel as TEM modes
- Note that the wave length of 50Hz = 6 million metres

CONCLUSION

- Electrical energy travels from source to load over wires as TRANSVERSE ELECTROMAGNETIC WAVES (TEM mode)
- Current drift* (Amperes) is a consequence of EM Waves NOT THE OTHER WAY AROUND
- This may be difficult to visualize in a pair of wires, but if you consider EM microwaves travelling down a wave guide, there will be surface currents in the wave guide walls. These are also drift currents. They are also the consequence of EM energy
- * A sample calculation of current drift is shown in appendix 1 of this presentation.

Appendix 1 ELECTRON DRIFT

The current drift rate through a conductor is in the order of mm/s. The drift rate of 1A through a 1mm diametre copper wire is worked out as follows:

Current density J = amperes per unit area (J = I/A) so J = 1Amp./(pi x r2) = 1/(3.14 x 0.00052) = 1.6 x 106

J can also be expressed as J = nevd

Transposing: vd = J/(ne)

Copper has an electron density n of 8.47 x 1028 m-3

With e = 1.6 x 10-19 coulombs of charge: ne = 1.4 x 109

Thus: vd = J/(ne) = (1.6 x 106) / (1.4 x 109) = 1.14mm/s

That is the nature of Electricity as I perceive it.

Thank you for attending Chuck Hobson BA,BSc(hons)

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