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ELECTROSTATICS
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 u=
p 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 he=
ar
the sound of the spark when it jumps.
In this =
PhysicsQuest you will investigate some applications of electrostatics=
.
TASK
You will read each
section by clicking on the links provided and answer the questions given.=
span>
PROCESS AND RESOURCES
Part I.=
TRIBOELECTRICITY
Rubbing silk on a glass rod makes the glass positive and the s=
ilk
negative. Rubbing fur on a hard rubber rod makes the hard rubber negative a=
nd
the fur positive. Whenever two different materials rub against each other i=
t 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".
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.
5. Briefly describe how the Van de Graaf&nb=
sp; generator
works.
6. What is wrong with the cartoon on the right?
Part III.=
b> 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.<=
/b>
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 sh=
ock
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 a=
re
different from each other.
10. =
b>Lightning can take many forms as it appears on the sky.
Briefly describe six forms of lightning.
11. =
b>Give three safety guidelines to follow during a=
lightning storm.
12. =
b>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=
span>
of the electron. He received the Nobel Prize for his work.
13.<=
span
style=3D'font-family:"Arial","sans-serif";mso-fareast-font-family:"Times Ne=
w Roman";
color:black'> Describe Millikan's experiment in detail using your own
words.
14. =
b>Draw a labeled sketch of the experiment.
15. =
b>Draw a neat-labeled free body diagram of the forces on the&nbs=
p;oil
drop.
Millikan's Oil Drop
Experiment Links:
=
Mov=
ie of the Oil-Drop Experiment
Physics of Millikan's Experimen=
t