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Trees are unpredictable, they don't always go where you want them to, sometimes they can snap and literally smack you in the head...I'm very careful when felling trees!!!! Dead trees are widow makers..

Enjoy...

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I am completely useless at DIY, if the wife wants a shelf putting up or anything like that, she gets the tool box out and does it herself, for one birthday the kids got together and brought her a pink

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We were never taught how to repair cars either. It was simply lack of money that taught me to replace plugs, filters, dynamos and water pumps etc. It was easy in the days of Cortinas and vivas. I wou

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He looks like he could be quite competitive on a quote, can you get his number? I have got some ridge tiles need re-bedding on my 3 storey property and a couple of fully mature oak trees felling?.

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My take on that electron and hole moving around stuff:

When electricity was discovered, it was generated by 'cells' (put more than one cell together and you get a battery). They decided that one end of the cell was positive and the other negative (still holds today with the + and - markings) and that the electrical current flowed from positive to negative. All well and good until someone later discovered that electrical current is actually electrons moving from the negative of the cell/battery, round the circuit to the positive. Trouble was that the convention was well established by then and it wasn't practicable to try to change it. If needed for clarity, we stick the word 'conventional' in front of 'current flow' to mean positive to negative, but generally we forget the detail and just assume current flows positive to negative. That's the way all circuit diagrams are drawn and the way all test gear is used.

... and those holes? The reason why electrons move is that there are vacant spaces ('holes') at the other end of the circuit for them to slot into. We can therefore pretend it's the holes moving positive to negative instead of the electrons moving negative to positive. That allows us to say that conventional current is the movement of holes.

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If you say electrons move into vacant holes then that would make sense, but on the army advanced signals course they said "holes flowed in the opposite direction to electrons" as John says "how can holes flow through solids?" If they said "holes seemed to flow in the opposite direction to electrons but they don't really" that would have made more sense (well it would have to me anyway). But of course on the exam you had to say what they wanted you to say, or you'd fail..

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If you say electrons move into vacant holes then that would make sense, but on the army advanced signals course they said "holes flowed in the opposite direction to electrons" as John says "how can holes flow through solids?" If they said "holes seemed to flow in the opposite direction to electrons but they don't really" that would have made more sense (well it would have to me anyway). But of course on the exam you had to say what they wanted you to say, or you'd fail..

Let's assume a theoretical wire is made from three copper atoms. Copper is good as its electrons are easily detached (that makes it a good conductor). Each copper atom has 29 positive protons and 29 negative electrons. Here’s the wire before we connect the battery:

Atom 1 has 29+ and 29- (balanced)

Atom 2 has 29+ and 29- (balanced)

Atom 3 has 29+ and 29- (balanced)

We switch on and the battery (+) takes an electron from Atom 1

Atom 1 has 29+ and 28- and so has a positive hole

Atom 2 has 29+ and 29- (balanced)

Atom 3 has 29+ and 29- (balanced)

Atom 1 takes an electron from Atom 2

Atom 1 has 29+ and 29- (balanced)

Atom 2 has 29+ and 28- and so has a positive hole

Atom 3 has 29+ and 29- (balanced)

Atom 2 takes an electron from Atom 3

Atom 1 has 29+ and 29- (balanced)

Atom 2 has 29+ and 29- (balanced)

Atom 3 has 29+ and 28- and so has a positive hole

Atom 3 gets an electron from the battery (-) to fill the hole; back to square one, ready for another round of 'pass the electron'

As you see, the hole has moved from Atom 1 to Atom 2 to Atom 3. Electrons have gone the other way. Nothing is passing through solids.

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Let's assume a theoretical wire is made from three copper atoms. Copper is good as its electrons are easily detached (that makes it a good conductor). Each copper atom has 29 positive protons and 29 negative electrons. Here’s the wire before we connect the battery:

Atom 1 has 29+ and 29- (balanced)

Atom 2 has 29+ and 29- (balanced)

Atom 3 has 29+ and 29- (balanced)

We switch on and the battery (+) takes an electron from Atom 1

Atom 1 has 29+ and 28- and so has a positive hole

Atom 2 has 29+ and 29- (balanced)

Atom 3 has 29+ and 29- (balanced)

Atom 1 takes an electron from Atom 2

Atom 1 has 29+ and 29- (balanced)

Atom 2 has 29+ and 28- and so has a positive hole

Atom 3 has 29+ and 29- (balanced)

Atom 2 takes an electron from Atom 3

Atom 1 has 29+ and 29- (balanced)

Atom 2 has 29+ and 29- (balanced)

Atom 3 has 29+ and 28- and so has a positive hole

Atom 3 gets an electron from the battery (-) to fill the hole; back to square one, ready for another round of 'pass the electron'

As you see, the hole has moved from Atom 1 to Atom 2 to Atom 3. Electrons have gone the other way. Nothing is passing through solids.

Simples, innit?

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? It's all Greek to me. :)

Well spotted ; Atom being Greek for that which can not be split ('a' means not and 'tom' means cut). Of course that name was chosen many centuries before Rutherford split the atom.

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Hmm, I suppose a hole is just a missing electron, a sort of not-electron (anti-electron? or is that a positron?) If you consider an electron as a physical thing (OK that's debatable) a hole would be a non physical thing as there's really nowt there. But I can imagine how holes seem to travel through solids, a bit like a wave in water where the water doesn't move much but the energy can travel for miles..

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