How to Determine Positive or Negative Charge

A known static charge will help identify an unknown charge.
••• Jupiterimages/Photos.com/Getty Images

When you rub two different materials together, the friction between them produces a positive charge in one and a negative charge in the other. To determine whether one of them has a positive or negative charge, you can refer to a triboelectric series, which is a list of known materials sorted by increasing negative charge. Rubber, for example, is lower on the list than wool, so stroking rubber with wool will reliably create a negative charge in the rubber. Knowing this, and armed with an electroscope for measuring charge, you can determine whether the charge of an object is positive or negative.

    Touch an electrical ground to remove stray static charges from your body. Touch the electrode knob on the foil electroscope to ground it.

    Stroke the hard rubber with the wool firmly several times, until you can feel a strong electrostatic buildup on the rubber.

    Touch the rubber to the electroscope knob. The foil in the electroscope should separate a few millimeters.

    Touch the object to the electroscope knob and watch the foil closely. If the foil separates farther, the charge on the object is negative. If the foil comes back together, the charge is positive.

    Things You'll Need

    • Foil electroscope
    • Hard rubber rod
    • Wool

Related Articles

How to Make an Electroscope for a Science Project
How to Build Up Static Electricity with Your Hands
How to Make a Negative Charge Magnet
How to Get Rid of Static Electricity in the Body
How to Make a Simple Electric Conductivity Apparatus
Will Batteries Discharge if You Throw Them in a Bag...
How to Find the Neutrons in the Periodic Table
How to Use a Resistor for 12 Volt to 5 Volt
Mechanism Description of a Manual Can Opener
How to Produce Electricity From an Apple
How to Make a Simple Circuit
List of the Advantages of Friction
How to Read Amps on an Analog Multimeter
How to Build Your Own Paper Foil Capacitor
How to Build a 120V AC to 12V DC Power Converter
How to Calculate Electrostatic Force
How Does an Object Become Positively Charged?
What Is a Ferrite Clamp?
How to Use a Multimeter to Test the Electrical Charge...

Dont Go!

We Have More Great Sciencing Articles!