Is there any difference between electrical conductivity and optical conductivity? How to explain it physically and is there any method available to connect them mathematically? If I calculate carrier concentration of a thin-film material by optical means ( say Swanepoel and Wemple-Didominico method) and electrical method ( say Hall measurement Van der Pauw method). Is there any difference between them and if yes how to connect them with a mathematical relation and how to explain it physically. Thank you.