Metal Type and Electical Resistance
What makes a metal more/less conductive than a different
metal? How does this affect its resistance?
A metal is a material that hold's one of its electrons very loosely. Very
little energy is needed to break the electron free. Actually, just the
little bit of heat energy present at room temperature will knock the
electron loose. In most cases, these loose electrons in the metal just
bounce around. Sometimes they rejoin with atoms for a while, only to be let
loose again later on. Conductivity is how easily these electrons move
through the metal. Atoms that grab loose electrons reduce conductivity.
Large atoms or atoms sitting close together also decrease conductivity: the
electrons have a greater chance of crashing into something.
Resistance is due to both conductivity and shape of the object. A more
conductive material passes electrons more easily: less resistance to
electron flow. A narrow object requires the electrons to be more tightly
packed together as they flow. This results in more collisions: greater
resistance. A longer object also increases resistance. Each electron
crashes into more atoms passing through a longer object.
Dr. Ken Mellendorf
Illinois Central College
Electrical conductivity in metals is related to the ease with which
electrons can flow through them. Not all metals offer the same opposition to
electron flow. By the way, the words, "conductivity" and "resistance" are two
(inverse) ways of referring to the same thing. Metals that have high
conductivity are of low resistance. Those showing high resistance, are those
of low conductivity.
Richard L. Hoffman
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Update: June 2012