Like the old chaps Pascal, Bramah, Reynold and other physicists found and defined natural laws and principles ruling for hydraulics, also electronics has its discoverers who have
determined laws, principles and values ruling for the work with these things.
Among the pioneers let’s mention Volta, Ampère, Farady, Hertz, Ohm, Watt and Coulumb and others as well as the Dane Ørsted.
Each of these physicians lent their name to the units and laws they discovered and described.
Funny enough, most of them all lived from the middle of the 18th century to the middle of the 19th centrury!
Now, in order to know what we are talking about, let’s take a closer look at the sizes we’ll come across in the coming chapters:
Volt – main measuring units for ETO
Volt, V, in formulae: U, unit of electrical voltage, measured with voltmeter.
Defined by the Italian Alessandro Volta
1 V is the potential difference between the ends in a lead yielding a resistance of 1 Ohm
in which there is a current of 1 A.
Ampère – main measuring units for ETO
Ampère, A, amp, in formulae: I, unit for measuring electric current, measured with ammeter.
Defined by the Frenchman André Marie Ampère (1775-1836).
1 A is the current liberating 1,118 mg silver of a solution of silver nitrate.
Ohm – main measuring units for ETO
Ohm, Ohm, ½ (the Greek letter Omega), in formulae: R (Resistance), measured with an ohmmeter.
Defined by the German Georg Simon Ohm (1787-1854).
1 ½ is the resistance at 0°C in a 106,3 cm long mercurial column with 1 mm2 section.
Watt – main measuring units for ETO
Watt, W. in formulae: P, unit for measuring electric power, measured with wattmeter or calculated after the formula
P = U * I
i.e. power = voltage multiplied by current.
Defined by the Scotchman James Watt (1736-1819). Better known for the steam engine.
Coulumb – main measuring units for ETO
Coulumb, (pronounced coo-long) Coul, unit for measuring amount of electricity which is
designated ampère-second or ampère-hour.
Defined by the Frenchman Charles Coulumb (1736-1806).
1 coul is equal to the amount of electricity moving with a current intensity of 1 A in one
1 ampèretime (1Ah) = 3600 coulumb
Farad – main measuring units for ETO
Farad, F, in formulae: C, unit for measuring the capacitor capacity.
To be calculated.
Defined by the Englishman Michael Farady
1 F is the capacity (charging) of a capacitor when the voltage is 1 V and the charge 1 coulumb.
Hertz – main measuring units for ETO
Hertz, Hz, cycle, designation of the frequency of an electric alternating current.
Defined by the German Heinrich Hertz (1857-1894).
1 Hz = 1 entire period per second.
Ørsted – main measuring units for ETO
Ørsted, unit for measuring electromagnetism.
Defined by the Dane H.C. Ørsted (1777-1851) who discovered the electromagnetism.