Electrostatics
Chapter 22
Electric Forces/ Charges
Charge (C) is a fundamental quantity of
electrical phenomena.
 Subatomic particles have electrical charges.
 These charges, when unbalanced create a
field.
 An atom with an unbalanced charge is
called an ion.
 Electrical charge cannot be created from
nothing or destroyed.

Coulomb’s Law
Coulomb describe the nature of
electoral force.
 Force = k*q1*q2/d2
 Where q represents charges, d
represents there distance, and k is
Coulomb’s Constant.
 This is analogous to gravitational force
equation.

Conductor and Insulators
Conductors have a loose electron in
the outer shell of the atom.
 Insulators keep their outer electrons
stuck to the atom.
 When electrons move it is more of a
pushing of atoms from one point to
another.

Semiconductors/
Superconductors
Semiconductors are material that can
be made to act as insulators or
conductors depending on certain
conditions.
 Superconductors are materials that
move electrons without any electrical
resistance.

Charging
Friction charging is done by gaining
electrons through physical contact.
 Induction charging happens when a
neutral bodies charges are separated
and one side is discharged.
 Lighting is a result of induction
charging.
 Lighting rods are used to rebalance
charges not to attract lighting.

Electric Field
Electric field is an aura that extends
around a charged object.
 Electric fields have magnitude and
direction.
 Field lines are used to represent the
aura around an object.
 When charges move they create a field
disturbance among other charged
particles

Electric Shielding
Electric fields can be shielded.
 One way is to use a Gaussian Sphere.
Inside an enclosed metal sphere the net
electric field is zero.
 This is used to insulate cables and
electrical components.

Electric Potential
Like mechanical energy, electrical
energy can do work.
 The possible energy to do work is called
electrical potential energy.
 Electric Potential is electric potential
energy for every unit of charge.
 Electric potential is also called voltage.

Van deGraaff Generator
Uses a rubber band to pull charges to
the sphere.
 The sphere collects charges till they can
over come the resistance of air.
 Air breaks down and an electrical
discharge returns the sphere to zero
potential.

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When the Van deGraaff generator is running how
strong is the electric field inside?
If the air breaks down at 3x106v for every meter
and a spark happens at 1ft (0.262m) what is the
voltage of the sphere?
How could the electrical discharges to the metal
rod be stopped?
What will happen to the metal pie pans when they
are placed on top of the Van deGraaff generator?