17-1: Electric Charge
• Like charges repel; unlike charges attract.
• The fundamental unit of charge (e) is
the charge on a single electron or proton (=1.6x10-19C).
• Charge is measured in Coulombs (C).
• Electric charges can move freely in conducors
(i.e. metals).
• Electric charges cannot move well through
insulators (i.e. glass, plastic).
• Conductors and insulators can be charged
by contact.
• Conductors can also be charged by induction.
• An insulator can receive a surface charge
by polarization.
17-2: Electric Force
| • Coulomb's Law - the electric force between 2
charges is proportional to the magnitude of the charges and inversely proportional
to the square of the distance between them |
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• k = Coulomb constant
• The electric force is a field force.
• The resultant electric force on any charge
is the vector sum of the individual electric forces on that charge.
17-3: The Electric Field
 |
• An electric field exists
around any charged object. |
 |
• Field lines are tangent to the electric
field vector at any point.
• The number of field lines are proportional
to the magnitude of the field strength.
• Electrostatic equilibrium - electric field
inside the conductor is zero; excess charge is on the conductor's outer
surface; electric field is perpendicular to the conductor's surface |
