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The electrically literate may find this somewhat simplified article redundant; or possibly amusing. They should check out Wikipedia for any gaps in their knowledge.

But I hope this will help those for whom Wikipedia is a bit too complicated and/or detailed.

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All cartoons from The New Yorker - 1925 to 2004

 

 

Think of water in a hosepipe

 

Electricity is a means of transporting energy from a source, like the wind, to a device you use to exploit that energy, like your electric toothbrush.

The usual way of explaining electricity is to use the simile of the flow of water in a pipe (a current of water).  We are all familiar with a hose pipe.  Its pressure is analogous to the voltage; and the flow of water is analogous to the current. 

 

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The author - almost two - learning about currents and voltage

 

The work that can be done in an hour, for example if you use the jet to spin a bicycle wheel or push leaves along a path, is the pressure (like Volts) times the current (like Amps) for an hour. 

You won’t be able to squirt the water from your hose far if there is no pressure or if there is no water.  You need both.  If the pressure falls the water ceases to flow.

It’s the same with a stream (current) of electricity making its way down a conductor; for example a wire. The electrical force acting on an electrical current provides the power to do work.

Most quantities in modern physics are named after an early natural philosopher or inventor.  If we had let tradition do it, each would probably be related by some strange number, like the number of feet in a mile; or pounds in a ton.  But most new physical values use the decimal system (the rationalised MKS or SI units: meter, kilogram, second).

A Watt is a measure of Power; the instantaneous capacity to do work; named after James Watt. 

Under this system we define one Watt as equal to one Volt (electrical  force) multiplied by one Ampere (current); or Amp for short.  Read More...

Using this simple relationship you can easily calculate that 1000 Watts of power (one kilowatt) can be carried by a current of 4.17 amps at 240 volts (240 x 4.17 = 1000)

But the same power requires only 0.002 amps at 500,000 volts (0.002 x 500,000 = 1000).  So when you turn on an electric kettle or toaster it will draw around 4 amps in your home at 240V but only 0.002 amps in the very high voltage grid to bring it from the generator in the power station.

Power exerted for a period of time is called Energy.  Physicists measure energy in Joules (1 J= 1Watt acting for 1 second).  But to get to a smaller working number electricity companies like to measure energy in kilowatt hours (1 kWh =  3,600 kJ = a thousand Watts acting for the seconds in one hour) 

When your bill comes, you get charged for the Energy, the number of kWh* you used, not Power (kW).

 

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*Terminology:  1000 Wh = 1 killowatt hour (kWh); 1000 kWh=1 megawatt hour (MWh); 1000 MWh = 1 gigawat hour (GWH), 1000 GWH = 1 terawatt hour (TWh).

 


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Travel

Denmark

 

 

  

 

 

In the seventies I spent some time travelling around Denmark visiting geographically diverse relatives but in a couple of days there was no time to repeat that, so this was to be a quick trip to two places that I remembered as standing out in 1970's: Copenhagen and Roskilde.

An increasing number of Danes are my progressively distant cousins by virtue of my great aunt marrying a Dane, thus contributing my mother's grandparent's DNA to the extended family in Denmark.  As a result, these Danes are my children's cousins too.

Denmark is a relatively small but wealthy country in which people share a common language and thus similar values, like an enthusiasm for subsidising wind power and shunning nuclear energy, except as an import from Germany, Sweden and France. 

They also like all things cultural and historical and to judge by the museums and cultural activities many take pride in the Danish Vikings who were amongst those who contributed to my aforementioned DNA, way back.  My Danish great uncle liked to listen to Geordies on the buses in Newcastle speaking Tyneside, as he discovered many words in common with Danish thanks to those Danes who had settled in the Tyne valley.

Nevertheless, compared to Australia or the US or even many other European countries, Denmark is remarkably monocultural. A social scientist I listened to last year made the point that the sense of community, that a single language and culture confers, creates a sense of extended family.  This allows the Scandinavian countries to maintain very generous social welfare, supported by some of the highest tax rates in the world, yet to be sufficiently productive and hence consumptive per capita, to maintain among the highest material standards of living in the world. 

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Fiction, Recollections & News

Wedding

 

 

Jordan Baker and Jeff Purser were married on Saturday 3rd of December 2011. The ceremony took place on the cliff top at Clovelly.

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Opinions and Philosophy

Discovery of the Higgs boson

 

 

Perhaps the most important physics discovery of my lifetime has finally been announced.  I say 'finally' as its existence has been predicted by the 'Standard Model' for a long time and I have already mentioned this possibility/probability in an earlier article on this website (link).

Its confirmation is important to everyone, not just to physicists working in the field of quantum mechanics.  Like the confirmation of the predictions of Einstein's Theory of Relativity we are now confronted with a new model of reality that has moved beyond an esoteric theory to the understanding that this is how the Universe actually is; at least as far as the Standard Model goes.

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