phys_ELECTROSTATICS

Electrostatics

The study of the effects of an unchanging (static) electric field upon stationary charged objects.

Electric charge

property of matter based upon charged particles (protons and electrons) in the atoms

*conserved and *quantized

Protons

positively charged particles

Electrons

negatively charged particles

neutrons

found in nucleus; neutrally charged particles

ion - negative and positive

a charged atom:

*negative ion= negative net charge
*positive ion = positive net charge

polar molecule

neutrally charged particle with positive lumped on one side and negative lumped on the other (think magnet)

Conductors

easily transfer electric charge; electrons aren't bound to particular atoms

Electric field inside is ZERO

insulators

don't easily transfer electric charge; electrons are bound to particular atoms

semi-conductors

in between conductors and insulators

Superconductor

a material that acts as an insulator at high temperatures and a perfect conductor at low temperatures

Critical temperature

temperature at which a superconductor begins to conduct electricity

Conduction

charge by contact - usu. by rubbing together

*creates static electricity

static electricity

electricity created through conduction (rubbing together);

Induction

charge through indirect contact; can only charge a CONDUCTOR

*brought near; makes polorized
*conductor's net charge stays 0 UNTIL TOUCHED BY ANOTHER OBJECT - which gives or receives electrons

electroscope

device that can detect electric charge (device charged by induction - gold leaves separate if charge brought near)

Electric force / Colomb's Law

similar to gravitational force:

*directly proportional to charge of objects
*inversely proportional to the square of the distance between them

Electric field

*developed by Michael Faraday

*force on a tiny positive test charge q divided by the magnitude of the test charge.

*N/C (units)

Electric Field Lines

Drawn to show the direction of the electric field on a particle

Electric Potential Energy

Energy by virtue of position near an electrical force

Electric Potential

(voltage) electrical potential energy per unit charge

Potential difference

only differences in voltage (electric potential) have meaning

*define zero point of electrical potential as infinitely far away from electric charge

Equipotential surfaces

surfaces with the same electric potential

Electron Volt

the energy acquired by a particle with a charge equal to that of an electron traveling through a potential difference of 1 V.

*MUST BE CONVERTED into Joules to be used in equations

Capacitors

store electric potential energy and electric charge

(Batteries store electric potential)

usually made by placing 2 conducting sheets close together

parallel plate capacitor

usual composition of a capacitor: made by placing 2 conducting sheets close together

Capacitance

(electric potential energy)

energy that can be stored by a capacitor

Ground

something with zero potential