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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

South Korea & China

March 2016

 

 

South Korea

 

 

I hadn't written up our trip to South Korea (in March 2016) but Google Pictures gratuitously put an album together from my Cloud library so I was motivated to add a few words and put it up on my Website.  Normally I would use selected images to illustrate observations about a place visited.  This is the other way about, with a lot of images that I may not have otherwise chosen.  It requires you to go to the link below if you want to see pictures. You may find some of the images interesting and want to by-pass others quickly. Your choice. In addition to the album, Google generated a short movie in an 8mm style - complete with dust flecks. You can see this by clicking the last frame, at the bottom of the album.

A few days in Seoul were followed by travels around the country, helpfully illustrated in the album by Google generated maps: a picture is worth a thousand words; ending back in Seoul before spending a few days in China on the way home to OZ. 

Read more ...

Fiction, Recollections & News

Lost Magic

 

 

I recently had another look at a short story I'd written a couple of years ago about a man who claimed to be a Time Lord.

I noticed a typo.  Before I knew it I had added a new section and a new character and given him an experience I actually had as a child. 

It happened one sports afternoon - primary school cricket on Thornleigh oval. 

Read more ...

Opinions and Philosophy

Losing my religion

 

 

 

In order to be elected every President of the United States must be a Christian.  Yet the present incumbent matches his predecessor in the ambiguities around his faith.  According to The Holloverse, President Trump is reported to have been:  'a Catholic, a member of the Dutch Reformed Church, a Presbyterian and he married his third wife in an Episcopalian church.' 

He is quoted as saying: "I’ve had a good relationship with the church over the years. I think religion is a wonderful thing. I think my religion is a wonderful religion..."

And whatever it is, it's the greatest.

Not like those Muslims: "There‘s a lot of hatred there that’s someplace. Now I don‘t know if that’s from the Koran. I don‘t know if that’s from someplace else but there‘s tremendous hatred out there that I’ve never seen anything like it."

And, as we've been told repeatedly during the recent campaign, both of President Obama's fathers were, at least nominally, Muslim. Is he a real Christian?  He's done a bit of church hopping himself.

In 2009 one time United States President Jimmy Carter went out on a limb in an article titled: 'Losing my religion for equality' explaining why he had severed his ties with the Southern Baptist Convention after six decades, incensed by fundamentalist Christian teaching on the role of women in society

I had not seen this article at the time but it recently reappeared on facebook and a friend sent me this link: Losing my religion for equality...

Read more ...

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