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.
Otto Von Guericke life and biography. Otto Von Guericke biography. Otto von Guericke is a German physicist, engineer and natural philosopher who built the first machine to create an electric spark. He used this electrical generator for many experiments with electricity, he was the first man to view electroluminescence.