Why is electricity blue?
Electricity only looks blue because we usually see electrical energy as it passes through air. Electrons in each atom of air gain energy from the electricity and jump to a more excited state. As the electrons return to their original energy level they release a photon of light. In air this photon appears blue, but other gases would produce different colours. The gases argon, phosphor, mercury and neon are used in this way to make the various colours in ‘neon’ lights.
WHO INVENTED THE BAROMETER?
Evangelista Torricelli became court scientist to the Duke of Tuscany in 1642. He experimented with fountains in Florence and a long tube over ten metres high filled with water that was in his house. In 1644 Torricelli described how he took a glass tube about one metre long, sealed at one end, and completely filled it with mercury, which is much denser than water. Then, holding his finger over the open end of the tube, he inverted it under the mercury contained in a large bowl and removed his finger. The mercury fell to a height of about 76 centimetres above
