The Laws of Ohm and Faraday

Electric current is due to the existence of a difference of potentials at the ends of a conductor this potential difference is called the voltage. According to Ohm s law the current I flowing through a given conductor is directly proportional to the voltage E and inversely proportional to the resistance R of that conductor 

The quantities I, E, and R are quoted in electrochemistry in so called international units. Among them there is the current unit one ampere (A or amp.), defined as a current that will deposit metallic silver from a solution of silver nitrate at a rate of 0,001118 grams per second. The unit of resistance is one ohm (Q) which is the resistance of a column of mercury of uniform cross section at a temperature of 0 °C, 106.3 centimeters high and having a weight of 14.4521 grams (it has a cross section of 1 sq. millimeter). 

Using Ohm s law the unit of voltage, called the volt (V), can be defined by the two precedent units as the potential difference required for a flow of current of one ampere through a conductor having a resistance of one ohm. In a closed electric circuit wo can write the equation E — IR, E meaning the electromotive force of the source of current connected to the circuit. Ohm s law can also be applied, however, to a part of an electric circuit then E = IR stands for the voltage or potential difference across the givon part of the conductor. 

The product of I in amperes and of time t in seconds expresses the quantity of electricity q in coulombs passed through the conductor  

One coulomb C or one ampere-second is a unit of quantity of electricity (electric charge) required to deposit 0,001118 grams of silver from a solution of silver nitrate regardless of the time during which the current passed through the electrolytic cell. This definition means that a current of one ampere represents a quantity of electricity equivalent to one coulomb per second. 

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