Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
A piece of metal (inside) is a neutral mixture of...[snip]...
positive ions and negative electrons. But the neutrality
does not apply to a region which is very close to the
outer surface. In a metallic layer close to the surface
electrons are being pushed toward the inside by
electrons which are outside. This creates a layer which
is positively charged and which attracts outside
electrons.
An electric surface tension? Mutual repulsion between
electrons exposes them to positive charges. The surface
tension analogy is quite obvious. A little bit like static
friction forces, more you pull larger the opposing force,
up to a limit. Is this an acceptable model for an
introductory physics course? It explains things in terms
of what students already know rather than in terms of
what some of them may possibly learn in the future.