At the beginning of this lesson you were asked the following essential questions:

  • What is an electric field, and how can it be described and analyzed?
  • What exactly is St. Elmo's fire, and why does it occur at the end of pointed surfaces?

You have learned that an electric field is the property of space surrounding a source charge that enables the source charge to exert forces on other charges that enter this region.  One way to describe electric fields is to use equations:

 

 

The direction of an electric field is determined by the direction of the electrostatic force experienced by a small positive test charge.  This can be used to describe electric fields in terms of patterns of electric field lines around source charges.

 

St. Elmo's fire is a consequence of the strong electric fields that develop along the sharp edges and points of conductors.  These electric fields are strong enough to ionize molecules of air, leading to the emission of light when free electrons combine with positively charged ions.

 

 

Assignment 5 (Part Two)

Open your saved Assignment 5 file, and complete Part Two.