while we're on the subject, i'll include a common misconception about electrolytics.....
i see a lot of posts on a popular audio forum, where people seem to think electrolytics have tons of ESL because of their construction. they surmise this because just about everybody has seen the results of a cap blowing up, with the long spindle of aluminum that results. first of all, this is usually small electrolytics with a case so small that it shoots off rather than rupturing, pulling apart the innards of the cap in this manner. second, they rarely see the construction of larger caps or the methods used to cancel or minimize ESL in the construction. we're all familiar with the aluminum foil/ wax paper cap illustration used in textbooks and even in crystal radio DIY kits, and know that electrolytic construction is similar, with the exception that a chemically treated dielectric is used instead (the chemical action on the aluminum creates a dielectric layer on the aluminum itself). what usually isn't shown is that the ends of the aluminum "coils" are usually crimped, and the wires for both plates terminate at the same end of the "coil". the crimp minimizes ESL by shorting the "turns" together, and the termination at the same end of the plates minimizes ESL by cancellation of mutual inductances, so the only real inductance left should be the lead inductance. of course no cap is perfect, and some "shortcuts" may be taken by manufacturers, causing more ESL. ESR in electrolytics is primarily a function of the formulation and the thickness of the oxide layer on the plates. you may have noticed that higher voltage rated caps have higher ESR. that's because of the thickness of the oxide layer, and the fact that the conductive portion of the plates is also thinner.