Electrical engineering - Basics Page 5

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Diagram 5: Normal electrocardiogram

Diagram 6: Electrocardiogram of a fibrillating heart

1.2 Fundamentals of physics

1.2.1 Structure of atoms

All elements we know are made of atoms.

Diagram 7: Shell model of the aluminium atom

The electrons on the external shell can detach themselves easily from the atom. Positively charged ions are resulting. This process is frequently occurring in metals since they have very few electrons on the external shell (e.g.: copper 1 bonding electron, aluminium 3 bonding electrons).

Diagram 8: Grid model of the structure of metals with bonding electrons (= "free electrons")

The positively charged ions form a regular grid. The much smaller bonding electrons (also called "free electrons") are moving in the space between the metal ions. The more free electrons exist the better is the conductivity of a substance or material. Non-conductive substances/materials do not have a crystalline structure and do not have any free electrons.


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