INTRODUCTION
Almost all of us are familiar
with static electricity because we can see and feel
it in the winter. On dry
winter days, static electricity can build up in our bodies
and cause a spark to
jump from our bodies to pieces of metal or other people's bodies. We can see,
feel and hear the sound of the spark when it jumps.
In this PhysicsQuest you will investigate some applications of
electrostatics.
PhysicsQuest
ELECTROSTATICS
TASK
You will read each
section by clicking on the links provided and answer the questions given.
PROCESS AND RESOURCES
Part I. TRIBOELECTRICITY
Rubbing silk on a glass
rod makes the glass positive and the silk negative. Rubbing fur on a hard
rubber rod makes the hard rubber negative and the fur positive. Whenever two
different materials rub against each other it is likely that one will leave
with more electrons than it started with and the other will leave with
less. This effect is known as "triboelectricity,"
from the Greek "tribein," or "to
rub".
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1. What is a triboelectric series?
2. Give two examples of materials that are more
likely to give up electrons, and two examples of materials that are more likely
attract electrons.
3. Which material is neutral in the triboelectric series?
Part II. ELECTROSTATIC GENERATORS
A variety of
electrostatic generators are available for
producing large amounts
of electric charge.
4. Name two electrostatic generators.
Van de Graaf Generator
5. Briefly describe how the Van de Graaf
generator works.
6. What is wrong with the cartoon on the right?
Part III. LIGHTNING
A spark is a stream of
electrons jumping across an air gap, heating the air until it glows and
expands. Certain conditions can cause enough static electricity buildup to
cause a spark or lightning.
7. Describe the creation of a ground strike of
lightning.
A single stroke of
lightning can heat the air around it to 30,000 degrees Celsius (54,000 F)! This
extreme heating causes the air to expand at an explosive rate creating a shock
wave that turns into a booming sound wave, the thunder.
8. Explain why there is a time difference between
the sight of lightning and the sound of thunder?
9. Name three types of lightning and
explain how they are
different
from each other.
10. Lightning can take many forms as it appears on
the sky.
Briefly describe six forms of lightning.
11. Give three safety
guidelines to follow during a lightning
storm.
12. Discuss in detail four lightning myths.
PART IV. DETERMINATION OF THE CHARGE OF THE
ELECTRON
In 1909 R. Millikan
performed an experiment to determine the
charge of the electron.
He received the Nobel Prize for his work.
13. Describe Millikan's experiment in detail
using your own words.
14. Draw a labeled sketch of the experiment.
15. Draw a neat-labeled free body diagram of the
forces on the
oil
drop.
Millikan's Oil Drop
Experiment Links:
Movie of the Oil-Drop Experiment
Physics of Millikan's Experiment