new MCAT Phs/Chem

current is measured in

amperes (amps)

ammeters measure

current in a SERIES circuit (ideally zero resistance)

conductance and resistance are

inversely proportional; one inc, the other dec

Ohms Law

V=IR (voltage = current x resistance)

volmeters measure

voltage in PARALLEL circuits (has high resistance, ideally no current)

resistance is measured in

Ohms

ohmmeters measure

resistance (usually simple circuit, known resistance)

capacitors

store charge

capacitance (C)

degree to which capacitor can store charge

capacitance equation

C = Q/V (Q = charge) aka Q=VC

capacitance is measured in

Farads (1 coulomb / 1 volt)

to increase capacitance (C=A/d) in a vacuum

inc area of plates or dec distance btwn the plates

or, increase dielectric constant

modified capacitance

C’

UNIFORM electric fields equation

E=v/d (volt / distance btwn plates)

GENERAL electric fields equation

E=f/q

magnetism

produced by the spin of elementary particles (+1/2 or -1/2)

diamagnetic materials

do not have a magnetic field; even number of orbitals cancel out

paramagnets

unpaired electrons with random spin; no net dipole

ferromagnets

unpaired electrons have a stable non-random spin; permanent magnets!!!

Tesla

large unit of magnetism (MRI)

strength of magnetic field equation (B)

B = I / 2 x pi x r (B is proportional to I)

stronger current (I) =

stronger field (B)

magnetic force is a

vector quantity (magnitude + direction)

magnetic fields ONLY exert force on

charged particles in motion at a degree other than 0

Lorentz Force

sum of magnetic force exerted on a charge by electrical and magnetic forces