Ninth Grade

 
 
 
 
 
9th Grade

How Shocking? Exploration

 

Have you ever seen lightning strike Earth? Lightning is a large static discharge. A static discharge is a transfer of charge between two objects because of a buildup of static electricity. A thundercloud is a mighty generator of static electricity. As air masses move and swirl in the cloud, areas of positive and negative charge build up. Eventually, enough charge builds up to cause a static discharge between the cloud and the ground.

 

        Not only does lightning produce a brilliant flash of light, it also generates powerful sound waves. The electrical energy in a lightning bold rips electrons off atoms in the atmosphere and produces great amounts of heat. The surround air temperature can rise to about 30,000 degrees Celsius- several times hotter than the sun’s surface. The heat causes air in the bolt’s path to expand rapidly, producing sound waves that you hear as thunder.

 

        The study of lightning and its relationship to electricity is not strange as many of you have heard the tale of Benjamin Franklin’s kite being struck by lightning. Fortunately, the kite was not struck by lightning as many think, but a negative charge from the air collected on a wire attached to the kite and traveled down the wet string. The sparks Franklin observed enabled him to show the true relationship between electricity and lightning.

 

        You see all objects that are charged, are charged in one of two ways:

 

  1. Charged by contact- meaning that electric charge is transferred by touching or rubbing. An example of this can be compared to how we have charged a balloon with wool or hair to create static electricity.

     

  2. Charged by induction- meaning that electric charge is transferred by the rearrangement of electrons on a neutral object caused by a nearby charged object. An example of this can be compared to a lab we performed when bringing a charged balloon near cereal. The cereal actually moved across the table due to a rearrangement in the cereal’s electrons.

     

 

 

 

 

 

 

 

 

Source: Edited from Glencoe Physical Science 2008

Go to: www.pbs.org/benfranklin/exp_shocking.html.

 

 

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