ohm's law

Ohm's law

Equation (4.2) is known as Ohm’s law in honor of Georg Simon Ohm (Fig. 4.1). The law clearly reveals that for a fixed resistance, the greater the voltage (or pressure) across a resistor, the more the current, and the more the resistance for the same voltage, the less the current. In other words, the current is proportional to the applied voltage and inversely proportional to the resistance. By simple mathematical manipulations, the voltage and resistance can be found in terms of the other two quantities:

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current

 Current

    If 6.242x 10^18 electrons drift at uniform velocity through the imaginary circular cross section  in 1 second,the flow of charge, or current,is said to be 1 ampere(A) in honor of André Marie Ampère . This is an enormous number of electrons passing through the surface in 1 second. The Current associated with only a few electrons per second would be inconsequential and of little practical value. To establish numerical values that permit immediate comparisons between levels, a coulomb(C) of charge was defined as the total charge associated with  6.242x 10^18 electrons. The charge associated with one Electron can then be determined from