*take nothing for granted!
Unless otherwise indicated all photos © Richard McKie 2005 - 2015

Who is Online

We have 41 guests and no members online

Translate to another language

What is electricity - really?

 

Above I invited you to think of electricity as a fluid of electricity running through a conductor that acts like a pipe.

According to our present conceptual model electricity is due to the movement of electrons in a conductor. Electrons are negatively charged fermions (particles that make up an atom) that are generally happy to hang around an atom to balance the positive charge of its nucleus.  Read More...

Electrons are envisaged as milling around in the general vicinity but often at a great distance, relative to the size of the nucleus, like planets around the sun.  The outer electrons define the physical size of an atom. Contrary to some pictures you might have seen they do not orbit elliptically like planets but occupy a space determined by their wave function and energy state.  They are happy bouncing around in this space unless something, like a photon of light or heat, encourages them to jump to another energy level. 

 

 

Conductors and insulators

Some elements, like the metals, bond to each other in such a way that outer electrons can pass energy on to the next; or perhaps get shared in one big cloud. 

By stimulating electrons to move we can make them carry energy along a conductor but this is more like the baton in a relay or an ‘Indian wave’ in a stadium than a flow of water.  Each one in the chain just gives the next one in line a ‘shove’; pass it on. The ‘shove’ goes down the conductor and after passing-on the ‘shove’ each electron continues to hang about as before. 

On the other hand non-metals tend to form molecules in which the electrons are not free to pass energy on.  A material in which no current can flow we call an insulator.  Read More...

Whether an atom is a metal or not depends on the number of protons in the nucleus.  After disregarding the first two (hydrogen and helium), elements can be lined up nicely by their proton count (roughly half their atomic weight) in a table: the first row pair of 8 then 18 then 32 columns wide; so that every 8th, 18th then 32nd is similar in properties; for example: a noble gas, a halogen or an alkali.  

This pattern was observed by chemists before it was explained.  Once recognised it allowed chemists to see the gaps and find the missing elements.  This regular pattern of repetition is called the periodic table of the elements. 

 

Periodic table

 

Quantum mechanics now provides a model predicting/describing/explaining this observed behaviour. 

Metals are not the only conductors.  Some non-metals like carbon have one form, graphite, which is a good conductor and another, diamond, which is a good insulator. 

Selenium, another non-metal, has semiconducting properties and was widely used before silicone in solid state rectifiers.  As a schoolboy I built several battery chargers and power supplies employing  selenium rectifiers which were then easily obtained from disposals stores.  

Black phosphorous is another non-metallic conductor.

If an electron is stripped from and atom (or it acquires extra electron) it is said to be ionised and if the whole atom is mobile; for example in a fluid (gas or liquid) the whole atom can act as a transport for electrons or of positive charge (an excess of protons). 

For example, salt water is a good conductor and even the earth (rocks and soil) can be used as the return conductor in a circuit. 

As kids we used this in our one-wire telephone to friends in neighbouring houses.

 

 

Add comment


Security code
Refresh


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


Travel

The United States of America – East Coast

 

 

In the late seventies I lived and worked in New York.  My job took me all around the United States and Canada.  So I like to go back occasionally; the last time being a couple of years ago with my partner Wendy.  She had never been to New York so I worked up an itinerary to show her the highlights in just a few days.  We also decided to drive to Washington DC and Boston. 

 

Read more ...

Fiction, Recollections & News

Julian Assange’s Endgame

A facebook friend has sent me this link 'Want to Know Julian Assange’s Endgame? He Told You a Decade Ago' (by Andy Greenberg, that appeared in WIRED in Oct 2016) and I couldn't resist bringing it to your attention.

To read it click on this image from the article:

 
Image (cropped): MARK CHEW/FAIRFAX MEDIA/GETTY IMAGES

 

Assange is an Australian who has already featured in several articles on this website:

Read more ...

Opinions and Philosophy

Tragedy in Norway

 

 

The extraordinary tragedy in Norway points yet again to the dangers of extremism in any religion. 

I find it hard to comprehend that anyone can hold their religious beliefs so strongly that they are driven to carefully plan then systematically kill others.  Yet it seems to happen all to often.

The Norwegian murderer, Anders Behring Breivik, reportedly quotes Sydney's Cardinal Pell, John Howard and Peter Costello in his manifesto.   Breivik apparently sees himself as a Christian Knight on a renewed Crusade to stem the influx of Muslims to Europe; and to Norway in particular.

Read more ...

Terms of Use                                           Copyright