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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

Hong Kong and Shenzhen China

 

 

 

 

 

Following our Japan trip in May 2017 we all returned to Hong Kong, after which Craig and Sonia headed home and Wendy and I headed to Shenzhen in China. 

I have mentioned both these locations as a result of previous travels.  They form what is effectively a single conurbation divided by the Hong Kong/Mainland border and this line also divides the population economically and in terms of population density.

These days there is a great deal of two way traffic between the two.  It's very easy if one has the appropriate passes; and just a little less so for foreign tourists like us.  Australians don't need a visa to Hong Kong but do need one to go into China unless flying through and stopping at certain locations for less than 72 hours.  Getting a visa requires a visit to the Chinese consulate at home or sitting around in a reception room on the Hong Kong side of the border, for about an hour in a ticket-queue, waiting for a (less expensive) temporary visa to be issued.

With documents in hand it's no more difficult than walking from one metro platform to the next, a five minute walk, interrupted in this case by queues at the immigration desks.  Both metros are world class and very similar, with the metro on the Chinese side a little more modern. It's also considerably less expensive. From here you can also take a very fast train to Guangzhou (see our recent visit there on this website) and from there to other major cities in China. 

Read more ...

Fiction, Recollections & News

The Cloud

 

 

 

 

 Chapter 1 - The Party

 

 

 

This morning Miranda had an inspiration - real candles!  We'll have real candles - made from real beeswax and scented with real bergamot for my final party as a celebration of my life and my death. This brief candle indeed!

In other circumstances she would be turning 60 next birthday.  With her classic figure, clear skin and dark lustrous hair, by the standards of last century she looks half her age, barely thirty, the result of a good education; modern scientific and medical knowledge; a healthy diet and lifestyle and the elimination of inherited diseases before the ban on such medical interventions. 

It's ironical that except as a result of accidents, skiing, rock climbing, paragliding and so on, Miranda's seldom had need of a doctor.  She's a beneficiary of (once legal) genetic selection and unlike some people she's never had to resort to an illegal back-yard operation to extend her life. 

Read more ...

Opinions and Philosophy

Electricity Pricing

 

 August 2012 (chapters added since)

 

 

Introduction

 

The present government interventions in electricity markets, intended to move the industry from coal to renewable energy sources, are responsible for most of the rapidly rising cost of electricity in Australia.  These interventions have introduced unanticipated distortions and inefficiencies in the way that electricity is delivered.

Industry experts point to looming problems in supply and even higher price increases.

A 'root and branch' review of these mechanisms is urgently required to prevent ever increasing prices and to prevent further potentially crippling distortions.

Read more ...

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