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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

Bolivia

 

 

In October 2011 our little group: Sonia, Craig, Wendy and Richard visited Bolivia. We left Puno in Peru by bus to Cococabana in Bolivia. After the usual border form-filling and stamps, and a guided visit to the church in which the ‘Black Madonna’ resides, we boarded a cruise boat, a large catamaran, to Sun Island on the Bolivian side of the lake.

Read more: Bolivia

Fiction, Recollections & News

A cockatoo named Einstein

 

 

 

A couple of days ago a story about sulphur-crested cockatoos went semi-viral, probably in an attempt to lift spirits during Sydney's new Covid-19 lock-down. It appears that some smart cocky worked out how to open wheelie-bin lids.  That's not a surprise - see below.  What is surprising is that others are copying him and the practice is spreading outwards so that it can be mapped in a growing circle of awareness. The cockies are also choosing the red (household rubbish) bins that may contain food, disregarding yellow (cans and bottles); blue (paper and cardboard) and green bins (garden clippings). Yet, now they have also been observed checking-out other potentially food containing bins.

One has even been observed re-closing the lid - presumably to prevent other birds getting to the food.

Back in the 1950's I was given a pet sulphur-crested cockatoo we named Einstein. I was in primary school and I didn't yet know who Einstein was. My father suggested the name - explaining that Einstein was 'a wise old bird'.

Read more: A cockatoo named Einstein

Opinions and Philosophy

The reputation of nuclear power

 

 

One night of at the end of March in 1979 we went to a party in Queens.  Brenda, my first wife, is an artist and was painting and studying in New York.  Our friends included many of the younger artists working in New York at the time.  That day it had just been announced that there was a possible meltdown at a nuclear reactor at a place called a Three Mile Island , near Harrisburg Pennsylvania. 

I was amazed that some people at the party were excitedly imagining that the scenario in the just released film ‘The China Syndrome’  was about to be realised; and thousands of people would be killed. 

Read more: The reputation of nuclear power

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