*be sceptical - take nothing for granted!
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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

Southern France

Touring in the South of France

September 2014

 

Lyon

Off the plane we are welcomed by a warm Autumn day in the south of France.  Fragrant and green.

Lyon is the first step on our short stay in Southern France, touring in leisurely hops by car, down the Rhône valley from Lyon to Avignon and then to Aix and Nice with various stops along the way.

Months earlier I’d booked a car from Lyon Airport to be dropped off at Nice Airport.  I’d tried booking town centre to town centre but there was nothing available.

This meant I got to drive an unfamiliar car, with no gearstick or ignition switch and various other novel idiosyncrasies, ‘straight off the plane’.  But I managed to work it out and we got to see the countryside between the airport and the city and quite a bit of the outer suburbs at our own pace.  Fortunately we had ‘Madam Butterfly’ with us (more of her later) else we could never have reached our hotel through the maze of one way streets.

Read more ...

Fiction, Recollections & News

My Art and Artists

 

 

One recreation that I find very absorbing is drawing and painting. 

Having once been married to an exceptionally talented artist (now Brenda Chat) I do not pretend great skill or insight.

I always drew and painted but living with Brenda was like someone who has just mastered ‘chopsticks’ on the piano being confronted by Mozart. 

Our daughter Emily has inherited or acquired some of her mother’s skill and talent.  

Emily and I once attended life classes together and I am awed by her talent too.  One of her drawings hangs behind me as I write.  It is a wonderful pencil study of a life class nude. 

Read more ...

Opinions and Philosophy

Gone but not forgotten

Gone but not forgotten

 

 

Gough Whitlam has died at the age of 98.

I had an early encounter with him electioneering in western Sydney when he was newly in opposition, soon after he had usurped Cocky (Arthur) Calwell as leader of the Parliamentary Labor Party and was still hated by elements of his own party.

I liked Cocky too.  He'd addressed us at University once, revealing that he hid his considerable intellectual light under a barrel.  He was an able man but in the Labor Party of the day to seem too smart or well spoken (like that bastard Menzies) was believed to be a handicap, hence his 'rough diamond' persona.

Gough was a new breed: smooth, well presented and intellectually arrogant.  He had quite a fight on his hands to gain and retain leadership.  And he used his eventual victory over the Party's 'faceless men' to persuade the Country that he was altogether a new broom. 

It was time for a change not just for the Labor Party but for Australia.

Read more ...

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