How to Build Farad-Sized Capacitors

The unit of measure for the capacitance of a capacitor is the farad. There are three factors that determine capacitance: The first factor is the plate surface area. Larger plates yield more capacitance. The second factor is the distance between the plates.The closer the plates are to one another (without touching), the higher the capacitance. The third factor is the dielectric constant of the insulating material between the plates. Mica has a higher dielectric constant than air and is therefore a common dielectric used in capacitors. To get a feel for how all three factors affect the farad value of a capacitor, it is useful to build a few capacitors and compare their overall capacitance values.

Things You'll Need

  • Aluminum foil
  • Wax paper
  • Copper wire
  • Tape
  • Candle
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Instructions

    • 1

      Cut 4 strips of wax paper measuring 4 inches by 37 inches. Cut 4 strips of aluminum foil measuring 3.5 inches by 36 inches.

    • 2

      Lay one strip of wax paper on a flat surface. Layer a strip of aluminum foil centered on the strip of wax paper. Tape a 6-inch piece of copper wire to the top, right hand corner of the foil, overlapping the foil with one inch of copper wire. The excess wire should extend above the layers.

    • 3

      Place alternating layers of wax paper and aluminum foil on the initial layer of wax paper and aluminum foil. Tape one end of a second 6-inch piece of copper wire to the bottom, left hand corner of the last layer of aluminum foil, overlapping the foil with one inch of copper wire. The excess wire should extend below the layers.

    • 4

      Roll the layers from one end to the other as tightly as possible. Wrap tape around the roll to prevent it from unraveling.

    • 5
      After charging and measuring a capacitor, label its value for future use.

      Light a candle and drip melted wax over each end of the roll to seal the capacitor. The capacitor is now ready for charging and measuring its capacitance.

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