"Project-O-Scope" Electroscope

Jane Pafundi

"Project-O-Scope" Electroscope Materials

  A device used to measure electrostatic charges.

 
                                                    
 
 
 
  • Description of Equipment
    • Electroscope
        A. Transparent piece                  B. Torsion style needle
              of plexi-galss                           


    C. An aluminum electrostatic shield

    D. Charging and grounding plate

  • Principles illustrated
  • Demonstrates the principles of electrostatics.

     
    Producing a negative charge:
     
        1. Ground the "Project-O-Scope" by touching the contact plate with your hand.
        2. Rub an ebonite rod with wool.
        3. Slide the rod slowly across the charging plate.
        4. The "Project-O-Scope" now has a negative charge.
     
    This occurs due to the negative electrons transferred from the wool to the rod and then to the contact plate. Since the "Project-O-Scope" started with equal amounts of protons and electrons it had no charge. After the rod was touched to the contact plate the electrons from the rod repelled the electrons in the plate into the electroscope producing a negatively charged electroscope.        

        

              

    Negatively Charged Electroscope

     
     
    Producing a positive charge:
     
        1. Ground the "Project-O-Scope" by touching the contact plate with your hand.
        2. Rub an acrylic rod with fur.
        3. Slide the rod slowly across the charging plate.
        4. The "Project-O-Scope" now has a positive charge.
     
    This occurs due to the positively charged rod attracting the negatively charged electrons from the contact plate producing a positively charged electroscope.
     
     
     

    Positively Charged Electroscope

     
      
    Testing an Unknown Charge:
     
        1. Charge the electroscope negatively as explained above.
        2. Bring the unknown charge near the charging plate.
        
                If the needle's deflection increases the unknown charge is a negative charge.
     
    This shows there is an additional negative charge by adding to the needle's deflection.
     
                If the needle's deflection decreases the unknown charge is a positive charge. 
     
    This shows there is a positive charge by reducing the deflection or taking away some of the negative charge.
     
      

    Testing an Unknown Charge

     

    Triboelectric Series:

    The following is a Triboelectric Series for many household items.  The further away items are on the list the easier it is to produce a charge when they come into contact with each other and then are separated. Positive items in the series are at the top, and negative items are at the bottom:

    Triboelectric series:
    Most positively charged
    +
    Air
    Human skin
    Leather
    Rabbit's fur
    Glass
    Quartz
    Mica
    Human hair
    Nylon
    Wool
    Lead
    Cat's fur
    Silk
    Aluminum
    Paper (Small positive charge)
    Cotton (No charge)
    0
    Steel (No charge)
    Wood (Small negative charge)
    Lucite
    Amber
    Sealing wax
    Acrylic
    Polystyrene
    Rubber balloon
    Resins
    Hard rubber
    Nickel, Copper
    Sulfur
    Brass, Silver
    Gold, Platinum
    Acetate, Rayon
    Synthetic rubber
    Polyester
    Styrene (Styrofoam)
    Orlon
    Plastic wrap
    Polyurethane
    Polyethylene (like Scotch tape)
    Polypropylene
    Vinyl (PVC)
    Silicon
    Teflon
    Silicone rubber
    Ebonite
    Most negatively charged

    From: http://en.wikipedia.org/wiki/Triboelectric_effect

    Related Topics:

    • Static electricity shocks
    • Clothes sticking to you
    • Lightening
    • Balloon Sticking to your hair

    Additional Links:

    http://commons.bcit.ca/physics/demos1103/DEM/DEM01A.htm

     

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    Jane Pafundi,
    Sep 6, 2009, 3:36 PM
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