Really, after I became an electrical (control) engineer, until now i do not know why capacitors like Electrolytic and Tantalum Ones, have polarity. can anybody answer me please?
I do not know if i am in the right place to ask this question but i am trying.
I need to select a light source so i can achieve a 500 lux on surface of 12mX0.5m, but the problem that i must put the source on a distance of 25m to 30m.
I tried to search for light sources but the problem that...