Just a couple of physics notes: I wrote r as a scalar. This is the magnitude of the vector r.; The 1 over 4πε 0 is just a constant.; Electric potential is a scalar quantity, not a vector.

Data Visualization - Plotly and Cufflinks. Plotly is a library that allows you to create interactive plots that you can use in dashboards or websites (you can save them as html files or static images) ...