Download Electrostatics PP complete

How can an object
be charged and
what affect does
that charge have
upon other objects
in its vicinity?
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What makes up all matter?
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What does it mean to be “charged”?
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What is GROUNDING?
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What are the (names &) methods of charging?
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What are insulators & conductors?
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Hey wait, what IS charge? A measurement, a
concept….?
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What do charged objects do? (to other objects)
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Matter is made of Neutrons, Protons and
Electrons
Protons have POSITIVE charge
Electrons have NEGATIVE charge
Neutrons are uncharged
Which has “more” charge?
Which charges move to charge an object?
Why do they move?
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This term is used for the process that “uncharges” a charged object.
It is performed by contacting a charged
object to an object that can give, OR receive
___________ charges, so that the initially
charged object is made neutral.
It can (partially) happen w/o contact when
one object that is highly charged discharges
across a gap – that is a spark
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Charging by :
◦ Friction
 Materials rubbed “against” each other transfer …
◦ Conduction
 A charged object is brought in contact with a conductor and there is a
transfer of …
◦ Induction
 A charged object is brought NEAR a conductor, the conductor is grounded,
there is a transfer of…..
the ground is removed, and finally the charged
object is moved away from the conductor
◦ Polarization (not really charging, as a polarized object’s NET charge can be zero )
 A charged object is brought near a neutral conductor, electrons on the
conductor move (toward, or away from the charged object) and then the
polarized object behaves as if it has the ________ charge as the object that
caused the polarization.
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A good CONDUCTOR allows negative charges
to travel around through the material making
up the conductor, with very little RESISTANCE.
A good INSULATOR makes it very hard for
negative charges to travel around through the
material making up the insulator. These have
a lot of RESISTANCE.
A SUPERCONDUCTOR is a material that allows
negative charges to flow through it without
any RESISTANCE.
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The SI unit for charge is the COULOMB (C)
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The charge of one electron is -1.6x10-19C
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The charge of one proton is +1.6x10-19C
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The quantity of charge equal to 1.6x10-19C is often
written as e so the charge of one electron is –e
To calculate the charge of a certain number of
electrons or protons, use the equation:
Q = +ne
where Q is quantity of charge, and n is the # of charge carriers
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To calculate the charge of a certain number
of electrons or protons, use the equation:
Q = +ne
where Q is quantity of charge, and n is
the # of charge carriers
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Opposite charges attract and like charges repel
Charged objects can attract neutral objects, by
polarizing the neutral objects.
Electrons are the only charges to get transferred
The force between charged objects can be
mathematically described by Coulomb’s Law
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Electroscope Investigation
PCR Static Electricity Lessons 1&2
CYU
◦ Lesson 1: a(1), b(1-6), c(all), d(1-3), e(1,2,4,5,6)
◦ Lesson 2: a(3,4), b(4), c(all), d(all)
1. If one million electrons are added to the top of a Van de Graff
generator, what is its charge in coulombs?
2. Use the negatively charged wand to charge the electroscope by
CONDUCTION. Remove the wand, then bring it back near scope.
◦ You observe:
3. Ground scope. Use the negatively charged wand to charge the
electroscope by INDUCTION. Remove the wand, then bring it back
near scope.
◦ You observe:
◦ Charge the glass with the cloth. Bring it near the charged scope. You
observe:
4. Record the four steps to charging the scope by induction. Do
you know what goes in in each of the four steps?
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But wait, what IS force?
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When does an electric force occur?
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What factors affect the size and direction of
the electric Force on an object?
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|Fe|(N) and Q1(C)?
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|Fe|(N) and Q2 (C)?
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|Fe|(N) and d (m)?
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Use the Gizmo simulation: Coulomb Force
Go to explorelearning.
Username: physics_south
Password: Einstein
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Fe = k(Q1 Q2)/d2
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F e:
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k = 9 x 109 (Nm2/C2)
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d:
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Q1 & Q2 are:
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The concept of a field is utilized by
scientists to explain the surprising force
phenomenon that occurs in the absence of
physical contact.
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The electric field is a ratio, comparing the
size of the force on a charged object to the
size of the charge
E=Fe/Q
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Fe=EQ
A slightly charged object in an electric field
will experience a small electric force, while
a heavily charged object will experience a
____________ force.
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As the distance from a charged object
doubles, the electric field ________________
Ex: If a small “test charge” is 0.40m from the
center of a charged Van de Graff, it
experiences an electric force F. How big is
the force when the test charge is:
a) 0.80 from the center?
b) 1.20m from the center?
c) 0.20m from the center?
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The field “lines” are really arrows that show the
direction of force on a positive “test” charge, and
show field strength by how closely the lines are
spaced
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Electric Field Lines for Two (different,
isolated) Point Charges
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Skim PCR Static electricity 4C, and complete
the CYU questions
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Complete WS on Electric Fields
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Play Electric Field Hockey
◦ Google Phet, go to play with sims, Physics,
electricity