: a very large amount or number: an amount that is much greater than what is necessary. A plethora of books have been written on the subject. a plethora of information. [+] more examples [-] hide examples [+] Example sentences [-] Hide examples. a very large amount or number: an amount that is much greater than what is necessary. A plethora of books have been written on the subject. a plethora of information. [+] more examples [-] hide examples [+] Example sentences [-] Hide examples.
Ohm's law defines the relationship between the voltage, current, and resistance in an electric circuit: I = V / R. The current is directly proportional to the voltage and inversely proportional to the resistance.
The resistance of a given conductor depends on the material it is made of, and on its dimensions. For a given material, the resistance is inversely proportional to the cross-sectional area; for example, a thick copper wire has lower resistance than an otherwise-identical thin copper wire.esistivity and conductivity are reciprocals : . Resistivity is a measure of the material's ability to oppose electric current. This formula is not exact: It assumes the current density is totally uniform in the conductor, which is not always true in practical situations.