A correlation is a single numerical value that is used to describe the relationship between two variables. All correlations have strength and direction. When two variables have a positive correlation, that means the two variables move in the same direction. The closer a positive correlation is to 1, the stronger it is.
William Gilbert discovered electricity, not Nikola Tesla. Nikola Tesla invented things. not discovered electricity. Again, William Gilbert discovered it and named it. He did this in the 1600s. It wasn't Nikola Tesla.
The first practical use of static electricity was the âelectric pistol,â which was invented by Alessandro Volta (1745-1827). An electrical wire was placed in a jar filled with methane gas. When an electrical spark was sent through the wire, the jar would explode.