Capacitor: Storage of Charge

From UO Physics Demonstration Catalog

Return to Capacitance

Description:

Two 5000 microfarad capacitors are connected in parallel. The capacitors are charged to 70 Volts using a regulated High Voltage Power Supply. . They will hold their charge until discharged with a screwdriver. This produces a spark and a very loud "pop". Refer to video.

SAFETY IS EXTREMELY IMPORTANT

  • The Power Supply is regulated so lethal currents are possible, Do not physically touch the leads on the capacitor or Power Suppl,y.,
  • OBSERVE POLARITY: Electrolytic capacitors will explode if they are connected backwards.
  • Put Capacitors behind a shield
  • Do not exceed 70 Volts,. Read the RED Analog Scale on the Power Supply.
  • When the capacitor is charging, Voltage on the meter will go to Zero and current will be high until Capacitor is charge. Then the current will go to zero and the Voltage will return to 70V.
  • Carefully Disconnect the + wire banana plug from the Power Supply with one hand.
  • When Ready, discharge the capacitor with the large screwdriver. It will make a loud Pop, Sparks will fly, and there will be a welding mark on the screwdriver!
  • Discharge the capacitor a few more times to make sure all residual charge is neutralized.

Location: