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Explanation of the Detection of Static Electricity by Ron Kurtus - Succeed in Understanding Physics. Also refer to physics, electrostatic induction, electroscope, electronic amplification, attract, repel, electrons, negative, positive, electrostatic locator, School for Champions. Copyright © Restrictions
Detection of Static Electricity
by Ron Kurtus (revised 22 January 2009)
The principle of electrostatic induction is often used to detect whether there are static electrical charges on the surface of some object. Electrostatic induction brings opposite electrical charges to the surface of a material and can be combined with the property that like charges repel to demonstrate the existence of static electricity.
The most common static electricity detector is the electroscope. Electronic amplification of the induced charges is another method to detect static electricity.
Questions you may have include:
- How can you use the property that opposites attract?
- How does an electroscope work?
- What is an electrostatic locator?
This lesson will answer those questions. There is a mini-quiz near the end of the lesson.
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Induction plus opposites attract
When you bring an item with a static electric charge near an object that is not charged, the electric field surrounding the static electric charges will induce or draw the opposite electrical charges toward the surface of that material. This works the best with materials that conduct electricity, but it will also work with most other materials to a lesser degree.
If the neutral item is lightweight, it will be drawn toward the other item once the opposite charge is induced. A simple experiment to demonstrate this method of detecting the presence of static electricity is to pick up some pieces of tissue with a comb you have run through your hair or a balloon that was rubbed on wool. Or you could attract a pith ball or small roll of paper that is hanging on a string.
In other words, you could use a lightweight object on a string as a static electricity detector. You would just bring it close to the other object to see if it is attracted.
You can even use the hairs on your arm to detect static electricity. The hairs will stand on end and point toward the static charge.
Electroscope
An electroscope is a device that detects static electricity by using thin metal or plastic leaves, which separate when charged.
An object with a suspected static electric charge is brought near the metal plate or ball of the electroscope. Electrical charges move to the metal and down to the foil leaves, which then repel each other. Since each leaf has the same charge (positive or negative), they repel each other.
Simple electroscope
A simple electroscope can be easily made.
A simple electroscope detects static charges
Professional electroscope
Electroscopes can also be used to measure the amount of static electricity.
Professional electroscope is calibrated to measure static electricity
A professional or laboratory electroscope is calibrated to not only detect static electricity, but also to determine the size of the charge or electrical field.
Electrostatic locator
An electrostatic locator is an electronic device used to detect and measure the electrostatic fields around objects. It uses electronic amplification of the induced charges and displays the amount on a meter.
Electrostatic locator detects static electricity
Unfortunately, this device is fairly expensive ($400), so it is primarily used in industry where static electricity may be causing problems.
Summary
Electrostatic induction brings opposite electrical charges to the surface of a material and can be combined with the property that like charges repel to demonstrate the existence of static electricity. The most common static electricity detector is the electroscope. Electronic amplification of the induced charges is another method to detect static electricity.
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Resources and references
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Books
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books on Static Electricity
Mini-quiz to check your understanding
If you got all three correct, you are on your way to becoming a Champion in Physics. If you had problems, you had better look over the material again.
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Detection of Static Electricity