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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.

 

 

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Travel

Brazil

 

 

In October 2011 our little group: Sonia, Craig, Wendy and Richard visited Brazil. We entered Brazil from Argentina near the Iguassu Falls.

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Fiction, Recollections & News

Skydiving

 

 

On the morning of May1st 2016 I jumped, or rather slid, out of a plane over Wollongong at 14,000 feet.

It was a tandem jump, meaning that I had an instructor strapped to my back.

 


Striding Confidently Before Going Up

 

At that height the curvature of the earth is quite evident.  There was an air-show underway at the airport we took off from and we were soon looking down on the planes of the RAAF  Roulette aerobatic display team.  They looked like little model aircraft flying in perfect formation.  

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Opinions and Philosophy

Manufacturing in Australia

Originally written in August 2011 - it might have been yesterday - so little has changed.

 

 

Manufacturing viability is back in the news.

The loss of manufacturing jobs in the steel industry has been a rallying point for unions and employers' groups. The trigger was the announcement of the closure of the No 6 blast furnace at the BlueScope plant at Port Kembla.  This furnace is well into its present campaign and would have eventually required a very costly reline to keep operating.  The company says the loss of export sales does not justify its continued operation. The  remaining No 5 blast furnace underwent a major reline in 2009.  The immediate impact of the closure will be a halving of iron production; and correspondingly of downstream steel manufacture. BlueScope will also close the aging strip-rolling facility at Western Port in Victoria, originally designed to meet the automotive demand in Victoria and South Australia.

800 jobs will go at Port Kembla, 200 at Western Port and another 400 from local contractors.  The other Australian steelmaker OneSteel also recently announced a workforce reduction of 400 jobs.

This announcement has reignited the 20th Century free trade versus protectionist economic and political debate. Labor backbenchers and the Greens want a Parliamentary enquiry. The Prime Minister who reportedly initially agreed has now, perhaps smelling trouble, demurred.

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