Volta and Ohm
By Illa Vij
ALESSANDRO Volta was born in a respectable but poor family in Como town in Italy, on February 18, 1745. As a young child, he was shy but when he began attending the public school in Como, he performed brilliantly.
In 1774, Volta was appointed as physics teacher in a school in his home town. In 1779, he held the chair of physics at the University of Pavia. He continued to work there for about 40 years. During all these years, he enjoyed teaching and alongside carried out tremendous research work. He travelled and visited many places and universities and met brilliant scientists like Lavoisier, Voltaire and Priestly.
While teaching at Como, he invented and perfected the electrophorous. This became a valuable tool for further research work. He proved the contact theory of electricity. He made two remarkable experiments using his own body. He placed a silver coin and a gold coin on different portions of his tongue and connected the two coins with a wire. A bitter taste was produced. In the other experiment he placed one metallic rod in his mouth and another against his eye. The two rods had been joined before he placed them in these positions. To his surprise, he experienced a sensation and saw light, the moment the contact was made. Volta had actually seen and tasted electricity.
His large number of experiments led to the invention of the Voltaic pile, in 1800. A continuous flow of electricity was made possible. Many honours were bestowed on Volta. In 1801, he gave a lecture and a demonstration in the French National Institute. The audience was so excited about it that before Volta could complete the lecture, the audience insisted upon a demonstration. Napolean Bonaparte was also present there. Everybody in the audience got a chance to receive a mild shock from Volta’s battery! He was again honoured by many awards and was made a Count and Senator of the realm of Lambardy by Napolean and was elected to the French National Institute.
At the age of 60, Volta wanted to resign from his professorship at the university, but Napolean would not let Italy’s greatest scientist resign. Volta continued to get his full pay and simply gave a lecture or two in a year, which satisfied Napolean!
In 1819, he finally retired and went back to his native town of Como and spent the rest of his life in peace and contentment. Volta’s discoveries led to many other discoveries made by other scientists.
Georg Ohm
Georg Ohm was born on March 16, 1787, in Erlangen, Germany. His father, Johann Wolfgang Ohm, was a locksmith. Having lost his mother at an early age, Georg was tutored by his father who loved mathematics and was good at it. Both Georg and his younger brother began loving mathematics.
Georg attended the local university at Erlangen. His study period at the university was not totally smooth. He had to take a break from his studies to begin teaching. Later, he again continued his studies, completing his Ph.D in 1811.
He published a book in 1817, and this helped him gain a teaching post at Cologne. In spite of being a teacher of mathematics, he had special love and interest in electrical researches. Further his locksmith training helped him build his own apparatus for research, which he could not afford to buy. Hard work and love for his research work, took him to great heights of success. Financial strains did not come in his way, and he overcome all odds. Success came the hard way. He came up with a 250-page treatise entitled Mathematical Measurement of Electrical Currents. Even today his work is considered a masterpiece. Unfortunately, at that time an influential critic condemned his work and Ohm was forced to resign from his post in the Jesuit College of Cologne. After six long dismal years, Ohm was appointed Professor of Physics at the University of Munich. Here he continued working till he died on July 7, 1854.
In 1841 when his work had been recognised and accepted, the Royal Society of London awarded him the Copley Medal. His laws of electric currents have proved to be very useful. In 1842 he was selected as a distinguished member of the Royal Society of London.
In 1881, the International Congress of Electrical Engineers awarded him with scientific immortality. Along with him, French scientist Ampere and Volta were also honoured.

Volt is a unit of electric measurement in the metric system known as the International System of Units. Its symbol is V. One volt is the potential difference (difference in the electrical state) between two points if 1 joule of work is done in moving a charge of 1 coulomb between the points. Differences in potential, often called voltage, are related to the energy of the electrical forces that “push” charges through a conductor. One volt of potential difference across a resistance of 1 ohm produces a current of 1 ampere.Most batteries and other sources of electromotive force are labelled according to their voltage. For example, many torches use two 1½ volt batteries. The most common instrument used to measure voltage is the volt-meter. The volt was named after Alessandro Volta. Ohm’s law is a mathematical formula that expresses the relationship between the electromotive force, electric current, and resistance in a circuit. This relationship was discovered by George Ohm in 1826. When applied to a direct-current circuit, Ohm’s law states that the electromotive force (E), measured it volts, equals the current (/) in amperes multiplied by the resistance (R) in ohms: .................................................E=IR When the law is used for an alternating-current circuit, resistance is replaced by impedance (Z), also in ohms. The flow of alternating current produces a counter-electromotive force, which resists the current. The strength of such resistance depends on how rapidly the current alternates. Impedance consists of this resistance, called reactance, combined with the circuit’s regular resistance to direct current.Engineers use Ohm’s law to determine the efficiency of circuits. For example, they can calculate how the flow of current will be affected by various arrangements of such circuit components as connecting wires, capacitors, and resistors.