Debora M. Katz
United States Naval Academy
Annapolis, MD
Physics is the fundamental Science
Put poetically,
physics illuminates the darkness
0. It’s a requirement.
1. We live in a high-tech
world so we need to
understand technology.
2. Physics is a tough course
that is used to weed us out.
My view
My students’
• Dogmatic
• Devoid of the
human element
• Does NOT
include stories
• No mistakes, no
missteps, no
debate
•In the broadest sense, a case study is an
educational story that is traditionally used
in medicine, business and law education.
•Case studies may be woven into
traditional teaching pedagogy or
developed for contemporary project-based
methods.
•A student working through a case study is
in the role of practitioner.
A student is in the role of a historical
scientist, exploring the process by
which great discoveries were made or
new technologies were invented.
In the middle of the 18th century, people loved to play with
electricity in their homes, but most people thought that
lightning was another phenomenon altogether—
explosions of atmospheric gas, something like the
explosions of gunpowder.
•Benjamin Franklin thought otherwise.
He believed that lightning was a colossal
electrical spark just like the small sparks
people found so amusing.
•Franklin collected charge from his flying
kite in a Leyden jar.
•Franklin showed that a Leyden jar
charged by clouds produced all the same
effects as Leyden jars charged in the
home.
•So he concluded that lightning is an
electrical phenomenon, like a giant spark.
• As people started
building taller structures, those
structures became more likely targets of lightning
strikes, causing fires, destroying property and lives.
Once Franklin
understood that
lightning was a giant
spark, he invented a
way to protect against
lightning strikes—the
lightning rod.
Franklin published the following recommendations for
lightning rods in Poor Richard (1753):
1. Just outside each building an iron rod should be
planted three to four feet in the moist ground.
2. The rod should extend 6 to 8 feet above the tallest
part of the structure.
3. On top of the rod should be a foot of brass wire
sharpened to a fine point.
.
The third point—the shape of the top of the rod—was
controversial. Franklin recommended that a pointed
lightning rod be used, but another scientist, Benjamin
Wilson, recommended a blunt-end lightning rod. The
Royal Society of London was asked to evaluate the
recommendations and decide which would make a better
device.
Your goal in this case
study is to decide
between Franklin’s
lightning rod and
Wilson’s.
In order for air to break down and become a conductor,
the electric field in the air must be 3 × 106 N/C. Let’s
assume that in order for a lightning rod to work, the
electric field at its surface must equal that breakdown
electric field.
Calculate the amount of charge on the surface of each
conductor.
The one with the least amount of charge is the better
design, because a smaller amount of charge on the
surface of the conductor means a smaller amount of
charge travels through the air.
Professor Katz,
I am really glad you enjoyed my project! It's one of the few things I did
right in the many technical courses here at the Academy lol I
really did love doing it and I hope your students have
enjoyed working on their projects also! I am sorry you cannot make
it but hopefully some people from your department will be able to go. I hope all
is well! You are a great teacher and your students are lucky to have you as a
Professor!
Very Respectfully,
Michelle
Using Historical Case Studies in
Introductory Physics
1.
2.
3.
Stealing God’s Thunder, Philip Dray
2005
Make to Stick, Chip Heath and Dan
Heath 2007
Science Teaching: The Role of
History and Philosophy of Science,
Michael R. Matthews 1994 (2000)
Debora Katz
Physics Department
United States Naval Academy
Annapolis, MD 21402
dkatz@usna.edu
http://www.usna.edu/Users/physics/dkatz/