THE VOLTAIC PILE

Alessandro Volta was born in 1745, in Como (Lombardia). In the year 1800 (century XIX) started doing his experiments when Luigi Galvani discovered what two different metals and the frog muscle produces eletricity. Alessandro Volta discovered that two different metals (zinc and silver) and a cardboard with water also produces electricity. The voltaic pile consist of thirty discs separated by cardboard with water.

Present aplications: battery, lantern, toys, clocks, mobile telephone, mp3, camera, portable computer...

The Radio

The Radio

G. Marconi is considered the inventor of the radio, of radiotelegraphy, to be precise (wireless telegraphy).

In 1.896 he sent the first radio signals and in 1.903 he managed to establish communication between Europe and America.

One of the historical facts that contributed to the birth of the radio was the emergency call sent by the Titanic in 1.912. It soon became a means of mass communication.

Other former discoveries that had an influence in the invention of the radio were:

- The telegraph,invented by Morse.

- The telephone, invented by Bell.

- The electromagnetic waves,discovered by H. Hertz.

Marconi's work helped later other inventions such as TV (1.926) created by J. Logie Baird.

Aplications and uses of the radio:

- Save human lives in diseases.
- Entertain, inform, communicate..
- Space missions, building of satelites...

Tania Sabín Salgado 3º C

The atmospheric pressure

The atmospheric pressure is the weight of air above the Earth's surface. The atmospheric weighs 1013 mp, 1 amt or 760mmhg. The atmospheric pressure it was inventes for Torricelli was discovered by a physicist and a mathematician Italian. In the 1643 it was discovered, in Florence.

It was discovered that Torricelli took a glass tube about one metre in length and filled witn mercury. Keeping the tube closed with mercury a finger, and introduced invested in a crock with mercury. When removing the finger found that the metal fell into a column whose height was 14 times lower than obtained when conducting the experiment with water. as I knew that mercury was 14 times heavier than water, deduced that boht columns fliud were supported equally counter weight, suspecting that only air was capable of doing such a force.

THE TRAIN

In 1803, Richard Trevithick invented the first steam engine at pressure and the first engine locomotive because he observed that it has more potency than the atmospheric pressure engines used until this moment.

Nine years later, in 1812, John Blenkinsop invented the first locomotive. It was a rack train, the railway have teeth that hook with the wheel. He believed that the wheels smooth slides on the railway also smooth.

Many years later, in 1879, Werner Von Siemens invented the first electric train. It was dragged by an electric locomotive. He unrolled a system for transmit electricity at locomotive.

In 1897 Frank Sprague invented the diesel train, he invented this, for that the train doesn’t have to a separately locomotive.

The invention of the train have many repercussions in the everyday life: At beginning of the modern age of the railway the traffic of travellers increased of surprising way. The coal and others merchandises were transporting of one station at other than by others transports and the receipts increase.

THE DYNAMITE

Alfred Nobel was a swede chemist that found the important prizes called Nobel.In 1867 he invented the dynamite.Also, in this year be born a important scientific called Marie Curie and other scientific called Michael Faraday die.

His investigation started later of the death of him brother because an explosion of nitroglycerine.He wanted to control these explosions.This way he created the dynamite, a plastic explosive that result of absorb the nitroglycerine on a porous material.

The dynamite remplaced at the nitroglycerine in demolitions and at the mining.Also, it was used for stuffing of the projectiles of artillery and stuffing of charge of military demolitions.Now, the dynamite was remplaced for anothers explosives because there were problems with its storage and with the production of nitroglycerine for its manufacture.