Presentation on theme: "1 -Voltage 伏特 - Coulomb 庫倫 - Ampere 安培 2 In 1745, Alessandro Volta was born in Italy. In 1774, he was 29-year-old, who was appointed professor of physics."— Presentation transcript:
2 In 1745, Alessandro Volta was born in Italy. In 1774, he was 29-year-old, who was appointed professor of physics in the Come high school. In 1779, he received a professorial appointment at University of Paria. In 1827, he died, at that time, he was already 82-year-old.
4 Discovered in 1775. A. Holding the insulating handle, the metal disk will removed from the top of the insulator. B. It’s removed and is sufficiently far from the vinyl sheet, the -ve will distribute to the metal disk until an equilibrium is reached. C. The charge disk is touched to the electroscope. This cause the deflection arm to repel from its centre.
6 Discovered in 1800. A. Different metals in contact with each other created electricity. B. Volta built a stack of alternating disc of zinc, blotting paper soaked in saltwater and silver. C. When he attached a wire to the top and bottom discs, he measured a voltage and current D. The current is produced because of a chemical reaction arising from the different electron-attracting capabilities of the two metals. E. This device became a “Voltaic Pile”.
9 In 1736, Charles Augustin de Coulomb was born in Angouleme, France. In 1777, he invented the torsion balance for measuring the force of magnetic and electrical attraction. In 1779, he published the Theory of Simple Machines, an analysis of friction in machinery. In 1806, he died in Paris, France. He had 70-year-old.
10 Coulomb -- A unit of electrical charge; the quantity of electricity passing in one second through a circuit in which the rate of flow is one ampere.
11 The force of attraction or repulsion between two charged bodies is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.
12 The force between two small, charged spheres is shown to be proportional to the magnitude of either charge and inversely proportional to the square of the distance between centers. This torsion balance device requires low humidity!
13 The unit of the current is named by Andre Marie Ampere. In 1775, he was born in the town of French -Lyon. In 1787, he was 12-year-old, he had already learned differentiation and integral calculus. In 1822, he discovered Ampere’s Law. In 1836, he died in Marseilles, at that time, he was 61-year-old.
14 A. According to the figure, if the current pass from bottom to top, it will produce the circular magnetic field. B. When the right hand hold the wire, the thumb is the direction of the induction magnetic field. C. The further of the distance of the wire, the weaker of the magnetic field produced.
15 The relationship of the current and the induction magnetic field can be explained by Ampere’s right hand rule. When the right hand hold the wire, the thumb stands for the direction of the current, and other four fingers stand for the direction of the magnetic field. So, when the direction of the current is the same, two parallel wires will attract each other. When the direction of the current is different, they will repel.
16 Discovered in 1822. Definition : The magnitude of the magnetic field is directly proportional to the current that pass through the same wire, but it is inversely proportional to the distance.