Terminology
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Valence Shell |
Electromotive Force |
Resistance |
Insulators |
Ohm |
Current |
Volt |
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Difference of Potential |
Voltage |
Conductors |
Semiconductors |
Coulomb |
Ampere |
Valence Shell
Outer electron shell of an atom.
The diagram on the left below is of a chlorine atom; the one on the right is of a copper atom.
Note that copper has only 1 electron in the valence shell - it is loosely bound resulting in copper being a good conductor.
Number of electrons each shell can accommodate (K is nearest the nucleus, Q is fartherest from the nucleus)
K (2), L(8), M (18), N(32), O (18), P (12), Q (2)
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Difference of Potential The force that moves electrons in a conductor
Electromotive Force (EMF) Another name for difference of potential
Voltage Another name for difference of potential |
Resistance (R)
Opposition to electron flow in a circuit
Conductors
Materials with low resistance
Insulators
Materials with high resistance
Semiconductors
Neither good conductors nor good insulators
Ohm (W)
Unit for measuring resistance.
Coulomb (C)
The charge of 6.24 x 1018 electrons
Current (I)
The flow of electrons. Represented by the symbol I. Measured in amps. One amp is the movement of one coulomb of charge past a point in one second.
Ampere (A)
Measure of current flow
Volt (V)
Unit for measuring voltage