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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 kilowatt hour (kWh); 1000 kWh=1 megawatt hour (MWh); 1000 MWh = 1 gigawatt hour (GWH), 1000 GWH = 1 terawatt hour (TWh).

 

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Travel

Canada and the United States - Part2

 

 

In Part1, in July 2023, Wendy and I travelled north from Los Angeles to Seattle, Washington, and then Vancouver, in Canada, from where we made our way east to Montreal.

In Part2, in August 2023, we flew from Montreal, Quebec, Canada, down to Miami, Florida, then Ubered to Fort Lauderdale, where we joined a western Caribbean cruise.

At the end of the cruise, we flew all the way back up to Boston.

From Boston we hired another car to drive, down the coast, to New York.

After New York we flew to Salt Lake City, Nevada, then on to Los Angeles, California, before returning to Sydney.

Read more: Canada and the United States - Part2

Fiction, Recollections & News

A Digger’s Tale

- Introduction

 

 

The accompanying story is ‘warts and all’.  It is the actual memoirs (hand written and transcribed here; but with my headings added) of Corporal Ross Smith, a young Australian man, 18 years of age, from humble circumstances [read more...] who was drawn by World events into the Second World War.  He tells it as he saw it.  The action takes place near Rabaul in New Britain. 

Read more: A Digger’s Tale

Opinions and Philosophy

When did people arrive in Australia?

 

 

 

 

 

We recently returned from a brief holiday in Darwin (follow this link).  Interesting questions raised at the Darwin Museum and by the Warradjan Cultural Centre at Kakadu are where the Aboriginal people came from; how they got to Australia; and when. 

Recent anthropology and archaeology seem to present contradictions and it seems to me that all these questions are controversial.

Read more: When did people arrive in Australia?

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