Static electricity is electricity at rest, which is an accumulation of electric charge. This source of energy is the opposite of moving electric charge, known as electric current. It is part of the study of phenomena resulting from electric charge, called electrostatics. Electrostatics is actually one of the foundations of knowledge about electricity. Static electricity is clearly the oldest known form of electricity. The earliest understandings of static electricity date back to experimenting by the Greeks in 600 BC. In fact, the word electricity comes from the Greek word electron, meaning Amber.
By the year 1600, many opinions had already been formed about electrostatics, which were later incorporated in the electrostatic force law. One idea was that there are two types of electricity, which were later named positive and negative by Benjamin Franklin. Another idea was that electric samples of the same kind repel each other, and those of different kinds attract each other. This later was named the law of electrical charges, and is essential to the understanding of electricity. A third idea was that if the distance between electric charges is increased, the force of attraction or repulsion decreases.
All matter is made up of very tiny particles called atoms. Atoms are made up of even smaller substances called subatomic particles. Scientific studies have found that some of these subatomic particles are charged with electricity. The electric charges are made up of two kinds – positive and negative. The positively charged particles are called protons, and the particles with negative charges are called electrons. In an atom, the protons are located in the center, or nucleus, and the electrons revolve in a series of orbits around the nucleus. All electric charges are caused by the combined effects of proton and electron charges.
The most common cause of static electricity is the rubbing together of two objects of different materials. Normally, materials have equal numbers of protons and electrons. The positive charges of the protons and the negative charges of the electrons cancel each other out, leaving no overall charge on the material. When rubbed, electrons move from the surface of one object to the surface of the other. The object that gains electrons has an overall negative charge, and the object that loses electrons has an overall positive charge, because it has more positive charges than negative charges.
All materials can be charged, but there are some that can be charged more easily than others. These materials are called conductors. Metal, for example, can take on electric charge just as other materials can. However, electrons can move more freely in metals because they conduct electricity more efficiently. Some other good electric conductors are water and the human body. There are also some substances that conduct little or no electricity. They are called insulators. Some common insulators are amber, glass, plastic, rubber, and dry wood.
The behavior of conductors and insulators can be easily explained. In some atoms, electrons in the outermost orbits are held loosely, and can be easily set free. They are called free electrons. Materials made up of these kinds of atoms have many free electrons, which makes them good conductors of electricity. Materials that have very few free electrons are good insulators. There are several different ways of creating static electricity. Most of the time it is caused by accident, and is sometimes considered a nuisance. A simple way to make static electricity is by combing your hair briskly on a dry day.
As you run the comb through your hair, your hair loses electrons and becomes positively charged. The comb gains electrons and becomes negatively charged. The static electricity created causes your hair to make a crackling noise as you comb it. Another way to place a charge on yourself is by walking across a rug on a dry day. The friction between your shoes and the rug transfers electrons from your body to the rug, giving your body a positive charge. Touching a doorknob or another metal object may cause electrons to jump from the object to your body. This could make a spark and make you feel a slight shock.
A third way to create static electricity is by rubbing a balloon on your shirt. The friction between the material and the balloon causes electrons to transfer from your shirt to the balloon. This gives the shirt an overall positive charge because it has more protons than electrons. The balloon takes on a negative charge because it has more electrons. Because of this, the balloon may then stick to your shirt or to another surface, such as a wall. The most common source of static electricity is lightning. Some scientists believe that raindrops tossed into the winds of thunderclouds create electric charge.
Some parts of the cloud become positively charged, and other parts become negatively charged. The tremendous amount of charge may jump between different parts of the cloud, or from the cloud to the ground. This creates the huge electric spark we call lightning. Lightning is the most dangerous form of static electricity. Benjamin Franklin’s famous kite experiment in 1752 could have proven rather foolish. During a severe thunderstorm, Franklin sent a kite soaring to incredible heights. At the base of the kite string, he attached a metal key. Electricity from the storm traveled down the kite string and struck the key.
Little did Franklin know that he could have been electrocuted. It was extremely dangerous, but he proved that lightning is electricity, and metal is a good conductor. Static electricity has many uses in everyday life. For example, the copying machines found in most offices are electrostatic copiers. To make duplicates of printed or written material, they attract negatively charged particles of a powdered ink called toner to positively charged paper. This attracts the ink to the blank paper, resulting in a quality duplicate of the original.
Another use of static electricity is in air cleaners called electrostatic precipitators. In these devices, a positive electric charge is put on particles of dust, smoke, bacteria, or pollen in the air. Negatively charged collector plates attract the positively charged particles out of the air, leaving much cleaner air. Through understanding the characteristics of static electricity, we have learned how, if properly controlled, it can enhance our lives. Once we learn how to harness the incredible power of a single lightning bolt, our knowledge of static electricity will be complete.