Hi, I tried to charche a plate capacitor with some 20 Volts but when disconnecting the cables from DC supply the voltage goes down to zero. Why is this? Cables too long? Didnt I wait enough or does a plate cap need high voltage (5000 Volts) and why does it? I am a theoretical physicist and have no idea about such stuff. I also fear somewhat using high voltage over non protected plates (if I touch the plates, I'm dead right?) so I would be very glad if it was possible to charge it with low voltage.