Dielectric Absorption.
Charge up an electrolytic capacitor and then time how long it takes for it to discharge to zero using a bleed resistor. Remove the resistor, wait a minute and read it again, there's more voltage left to come out. This is an example of dielectric absorption. It's like squeezing a sponge dry, and then some more seems to come out.
A polypropylene capacitor discharges faster and more completely than an electrolytic. In addition to electrolytic capacitors, some power supply designs use a big polypropylene cap (similar to start caps used on motors) to make reserve power more immediately available.
Charge up an electrolytic capacitor and then time how long it takes for it to discharge to zero using a bleed resistor. Remove the resistor, wait a minute and read it again, there's more voltage left to come out. This is an example of dielectric absorption. It's like squeezing a sponge dry, and then some more seems to come out.
A polypropylene capacitor discharges faster and more completely than an electrolytic. In addition to electrolytic capacitors, some power supply designs use a big polypropylene cap (similar to start caps used on motors) to make reserve power more immediately available.