Chapter 4 - Electrostatics and Magnetism

proton and electron, equal in magnitude

proton and neutron are equal in magnitude of charge, but neutrons have much greater mass than protons

insulators

not easily distribute charge over its surface and will not transfer that charge to another neutral object very well
- most non metals
- experimentally, usually serve as capacitors

conductor

charge distributed approximentally evenly upon the surface, able to transfer and transport charges
- generally metals

coulomb's law

quantifies the magnitiude of electrostatic force between two charges

just like every mass creates a gravitational field,

every charge sets up an electrical field around it

electric fields

exert force on charges that move through move into the space and region of these fields
- the character of repulsion or attraction of this force is dependent on the stationary test charge (Q) and the charge that enters the field (q) and if they are opposite charges

field lines

are imaginary lines that represent how a POSTIVE test charge would move in there presence of a the source charge
- field lines are closer together near the source charge and further apart the further away from the charge
- field lines closer together indicates a stronger electric field, field lines further apart indicate a weaker electric field

electric potential energy

energy that is dependent on the relative position of one charge with respect to another charge or to a collection of charges
- can define this as the amount of work necessary to bring the charge from infinitely far away to that pontoon

opposite charges are more stable the closer they are

these charges exert an attractive force and become more stable the closer they get, causing the potential energy to become an increasingly small negative number

similar charges are more stable the further away they are from one another

these charges exert a force of repulsion and become more and more stable the further away they become, this causes the potential energy to become an increasingly small positive number

electric potential

ratio of the magnitude of a charge's electric potential energy to the magnitude of the charge itself

negative charge moving in electric field

charge will move in a direction that increases its electric potential (from area of low electric potential to higher) (postive voltage)

postive charge moving in electric filed

charge will move in a direction to decrease its electric potential (negative voltage)

equipotential line

line on which the potential at every point is the same, the potential between any two points on the line is zero
- therefore, no work will be done moving a charge from one point to another along the line

moving test charge from one line to another

work is done when moving charge from one line to another but the work id only dependent on potential difference between the lines not the pathway (STATE FUNCTION)

electric dipole

two equal to opposite charges being separated a small distance from each other

perpendicular bisector of the dipole

equipotential line, the plane that lies halfway between +q and -q
- angle between this plane and the dipole axis is 90 degrees
- electric potential along this line is 0

magnetic field

mass movement of charge in the form of current through a conductive material or by pemanent magnets

diamagnetic material

made of atoms with no unpaired electrons and that have no net magnetic field, slightly repelled by a magnet

paramagnetic material

made of unpaired electrons that become weakly magnetized in the presence of external magnetic field, aligning the magnetic dipoles of that material w the external field
- aluminum, copper, gold

ferromagnetic materials

unpaired electron and permanent atomic magnetic dipoles, strongly magnetized when exposed to magnetic filed
- iron, nickel, cobalt

Lorentz force

sum to electrostatic and magnetic forces acting on a charge