* take nothing for granted    
Unless otherwise indicated all photos © Richard McKie 2005 - 2021

Who is Online

We have 140 guests and no members online

Article Index

 

 

 

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.

image010
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. 

 

image032
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).

 

image012

 

*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).

 


    Have you read this???     -  this content changes with each opening of a menu item


Travel

India and Nepal

 

 

Introduction

 

In October 2012 we travelled to Nepal and South India. We had been to North India a couple of years ago and wanted to see more of this fascinating country; that will be the most populous country in the World within the next two decades. 

In many ways India is like a federation of several countries; so different is one region from another. For my commentary on our trip to Northern India in 2009 Read here...

For that matter Nepal could well be part of India as it differs less from some regions of India than do some actual regions of India. 

These regional differences range from climate and ethnicity to economic wellbeing and religious practice. Although poverty, resulting from inadequate education and over-population is commonplace throughout the sub-continent, it is much worse in some regions than in others.

Read more ...

Fiction, Recollections & News

The Writer

 

 

The fellow sitting beside me slammed his book closed and sat looking pensive. 

The bus was approaching Cremorne junction.  I like the M30.  It starts where I get on so I’m assured of a seat and it goes all the way to Sydenham in the inner West, past Sydney University.  Part of the trip is particularly scenic, approaching and crossing the Harbour Bridge.  We’d be in The City soon.

My fellow passenger sat there just staring blankly into space.  I was intrigued.   So I asked what he had been reading that evoked such deep thought.  He smiled broadly, aroused from his reverie.  “Oh it’s just Inferno the latest Dan Brown,” he said.   

Read more ...

Opinions and Philosophy

Energy and a ‘good life’

 

 

 

Energy

With the invention of the first practical steam engines at the turn of the seventeenth century, and mechanical energy’s increasing utility to replace the physical labour of humans and animals, human civilisation took a new turn.  

Now when a contemporary human catches public transport to work; drives the car to socialise with friends or family; washes and dries their clothes or the dishes; cooks their food; mows their lawn; uses a power tool; phones a friend or associate; or makes almost anything;  they use power once provided by slaves, servants or animals.

Read more ...

Terms of Use                                           Copyright