Explanation of Static Electricity Sparks and Lightning - Succeed in Physical Science. Also refer to physics, Ben Franklin, kite, thunder, electric pressure, conductors, insulators, voltage, resistance, electric shocks, Ron Kurtus, School for Champions. Copyright © Restrictions
Static Electricity Sparks
by Ron Kurtus (revised 13 April 2008)
A spark is what you see when a stream of electrons jumps across an air gap, heating the air until it is white hot. It is often caused by a buildup and release of static electricity and is thus called an electrostatic discharge (ESD). A spark can be thought of an a miniature version of lightning seen in a thunderstorm.
, they heat the air T
glows and expands. Certain conditions can cause enough static electricity buildup to cause a spark or lightning. A spark often requires both a conductor and non-conductor. Lightning is an extreme example of a spark.
Questions you may have include:
- What are the conditions that cause a buildup of electrons?
- How do sparks occur?
- What is lightning and thunder?
This lesson will answer those questions. There is a mini-quiz near the end of the lesson.
Useful tools: Metric-English Conversion | Scientific Calculator.
(Note: If you want to find out how to stop getting shocks, see Controlling Static Electricity.)
Conditions for sparks
Sparks do not happen easily. They are violent occurrences that require special conditions. They need both non-conductors and conductors to occur. The way this happens can get complex. These conditions include walking on a carpet on a very dry day or the rapid movement of tiny water particles in a summer storm.
In the home
The Triboelectric Series shows that when certain materials are in contact, they can cause a great increase in electrical charges on the surfaces of those materials. This is typically the case in for sparks that people personally experience.
In the clouds
Normally water inhibits static electricity, but in the case of thunderstorms, there is so much movement of air and water droplets within the clouds that charges collect on the surface of the droplets. Enormous amount of charges can collect in the clouds, some positive (+) and some negative (−).
ADDED MAT'L
Most lightning occurs within clouds.
Turbulence within a cloud during a storm cause ice crystals to create an area of positively charged ions near the top of the cloud and a region of negatively charged electrons near the bottom of the cloud. Since the negative charges in the cloud repel negative charges on the ground, it causes the ground to become positively charged. when the amount of charges become sufficient, The electrons stream from the cloud and the positive ions stream from the ground. When they meets, a powerful surge of current shoots backward up the path, causing the lightning.
Sparks require conductors
You know that static electricity collects on the surface of non-conductors. But you seldom—if ever—see a spark fly from one non-conductor to another. The reason is that sparks need conductors, so that the electrons can freely move about and gather enough charges together to be able to jump from one material to another.
If you took a charged piece of plastic and put it next to some metal, there would be no spark. The charges are held on the surface of the plastic, so that they won't jump the air gap
Another good example of this concerns how you can get shocked with a spark. You are a conductor of electricity—although not as good as a piece of metal. The reason you conduct electricity is because the of salt in your blood and your cells. Now if you notice, you usually see sparks when you start to touch something metal—like a doorknob—or another person or animal.
So static electricity is formed and gathered on the surface of a non-conductor, but it must be then transferred to a conductor to cause a spark.
Charges move in conductor
When a conductor—like a metal rod—is brought near a charged non-conductor, the free electrons in the conductor will move to one end or the other of the rod, depending on whether the non-conductor surface is positive or negative.
Opposite charges in conductor move toward non-conductor
When the conductor is brought into contact with the non-conductor, the electrical charges on the surface of the non-conductor are "sucked" into the conductor. In other words, if negative charges are on the surface of the non-conductor, these electrons will move into the conductor. If positively charged atoms are on the surface, electrons from the metal or conductor will neutralize those atoms, resulting in an excess of positive charges in the conductor.
Now, if another conductor is brought near the first conductor, the same thing will happen. Since electrons can move so freely in a conductor, many may collect near the surface and actually jump across the air gap as a spark.
Anatomy of a spark
Air is a non-conductor of electricity and resists the movement of electrons through it. When the attraction or electrical pressure is great enough between objects with positive (+) and negative (−) charges—or even between a charged object and a neutral one—some electrons are able to overcome the resistance and jump the air gap. This electrical pressure is also called potential difference or voltage difference.
Heats up the air
Since air is a non-conductor of electricity, it does not readily let electrons pass through it. But if the attraction is great enough, some electrons will leave their material and fly to the other object. While they move through the air, may smash into and bounce off molecules or atoms that are in their way. This heats up the air. (See Heat for an explanation.)
Spark glows white-hot
Lower resistance
Now, the hotter the air is, the less resistance it gives the electrons. So as the air gets heated, more and more electrons start jumping over to the other side. This only heats the air even more, until it actually gets white-hot. That is the spark or bolt of lightning that you see and feel.
Electrons stop jumping
Once enough electrons have made the jump, the attraction is reduced and the flow stops. The spark quickly cools down and the air stops glowing. It is all over in a fraction of a second. Since this happens for such a short time, so you may only feel a slight discomfort from the heat of the spark. But if the spark is a bolt of lightning, it can cause an enormous amount of damage.
Spark plug
Summary
Static electricity is caused when friction causes electrical charges to build up on a surface of a non-conduction material. Its explanation comes from the Atomic Theory of Matter. Static electricity can cause sparks and other problems, but it also is useful in pollution control.
Be observant and discover more about electricity and about life
Resources
The following resources provide information on this subject:
Websites
Humans and Sparks - Preventing painful static sparks
Books
Top-rated books on Static Electricity
Mini-quiz to check your understanding
1. What is a spark made of?
2. What causes the noise of thunder?
3. What is the difference between a spark and lightning?
If you got all three correct, you are on your way to becoming a Champion in Physical Science. If you had problems, you had better look over the material again.
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Static Electricity Sparks and Lightning