electrostatics electrostatics - the study of electricity at rest
TRANSCRIPT
ELECTROSTATICS
• Electrostatics - the study of electricity at rest.
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ELECTROSTATICS
Electrical Forces arise from particles in atoms-can be either repulsive or attractive
Like charges repel.
-protons repel protons ( + + )
-electrons repel electrons ( - - )
Unlike charges attract. -protons and electrons attract each other
(+ -)
ELECTROSTATICS
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ELECTROSTATICSCharge – a property that is attributed with
attractive or repulsive behaviorIn the atom, by convention (general agreement),
electrons are assigned a negative charge (-)
protons are assigned a positive charge (+), and
neutrons are neutral (0).
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ELECTROSTATICSFacts about Atoms:
-positively charged nucleus surrounded by negatively charged electrons
-electrons are identical (same mass and same amount of negative charge)
-nucleus is made of positively charged protons and neutral neutrons
-all protons are identical (same mass and same amount of positive charge)
-all neutrons are identical (same mass)
ELECTROSTATICSAtoms have the same number of protons and electrons.
# of protons = # of electronsNeutral atom has a net charge of zero.
Atom with extra electrons has a net negative charge.
negative ion
Atom with less electrons has a net positive charge.
positive ion
Only electrons can be lost or gained - not protons or neutrons.
Atoms and Ions
UNIT OF CHARGE
Coulomb - SI unit of charge
- abbreviated C
1 Coulomb is the charge on
6.24 x 1018 electrons
The charge on 1 electron is
(1/6.24 x 1018) = -1.6 x 10-19 C
COULOMB’S LAWThe electrical force between charged particles is directly related to the charge of each particle and
inversely related to the square of the distance between the particles.
F = k q1q2
----------
d2
k = 9.0 x 109 N.m2
C2
COMPARE and CONTRAST
NEWTON’S LAW OF GRAVITATIONF = G m1m2 G = 6.7 x 10-11 N.m2
d2 kg2
COULOMB’S LAWF = k q1q2 k = 9.0 x 109 N.m2
d2 C2
COMPARE and CONTRAST
Newton’s Coulomb’s
Gravitation Electrical
Similarities
1. 1.
2. 2.
Differences1. 1.
2. 2.
COMPARE and CONTRAST
Newton’s Coulomb’s
Gravitation Electrical
Similarities
1. Product of masses 1. Product of charges
2. Inverse square law 2. Inverse square law
Differences1. Very small constant 1. Very large constant
(very small force) (very large force)
2. Attractive force only 2. Attractive and repulsive
INSULATORS and CONDUCTORS
Conductors - materials that allow electric charge to move easily - “loose” electrons
Examples:
Insulators - materials that do not allow electric charge to move easily
Examples:
CHARGING MATERIALS
• FRICTION - this is the process of adding or taking away electrons by moving objects across each other.
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CHARGING MATERIALS
• CONDUCTION OR CONTACT - the process of giving a charge to an object by touching it with another charged object.
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CHARGING MATERIALS
• INDUCTION - the process of charging an object by bringing another charged object near but not touching the object.
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CHARGE POLARIZATION
• An object can be electrically
polarized when one side of
the object is more negative
(or positive) than the other
side of the object.
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