Electricity and Magnetism Flashcards
unit of charge
coulombs
current run….
in the opposite direction of electrons
Universal Law of Conservation of Charge
every time a negative charge in created, a positive charge is created, and vice versa
Coulomb’s Law
F = Kq_1q_2/r^2
magnitude of force of repulsion or attraction between 2 charged objects
both gravitational and electric forces change inversely with…
the square of the distance between the centers of mass or charge
field
some type of distortion or condition in space that creates a force on a charge, or mass if gravitational field, or magnet if magnetic field
lines of force
represent a field, point in direction of field (positive to negative for electric fields), closer lines = stronger field
field lines point ____ for electric fields
positive to negative
electric field from point charge, E =
E = kq_1/r^2
force on charge in electric field=
F = Eq
potential energy of charge in E field=
force x displacement
U = Eqd
electric potential energy from point charge =
U = kq_1q_2/r
voltage
potential for work by an electric field in moving any charge from one point to another
V = Ed
units: J/C
voltage due to point charge
V = kq_1/r
equipotential surfaces
all points on surface are same voltage
electric dipole
created by two opposite charges with equal magnitude
resistivity
quantitative measure of substance’s resistance to flow of charge
resistance (R)
quantitative measure of an object of a particular shape and size to resist the flow of charge, in ohms
Ohm’s Law
V = iR
Kirchoff’s rule
amount of current flowing into any node must be the same amount that flows out
voltage around any path in a circuit must sum to zero
EMF
the voltage on a battery
capacitor
to temporarily store energy in a circuit in the from of separated charge
parallel plate capacitor
two plates fade from conductive material separated by a very small distance, one plate positive other plate same amount of negative charge
capacitance
ability to store charge per unit voltage, something with high capacity can store a lot of charge at low voltage
C = Q/V
energy stored by any shape capacitor
U = 1/2QV U = 1/2CV^2 U = 1/2Q^2/C
dielectric constant, k
the substance between the plates of a capacitor
must be an insulator, acts to resist the creation of an electric field and allows the capacitor to store more charge
resistors in series
Reff = R1 + R2 + R3…
resistors in parallel
1/Reff = 1/R1 + 1/R2…
capacitors in parallel
Ceff = C1 + C2 +….
capactiors in serioes
1/Ceff = 1/C1 + 1/C2.
electrical power
P = iV P = i^2*R P = V^2/R
direct vs. alternating current
direct = net movement of e-s is in one direction around circuit alternating = created by oscillating e-s back and forth in simple harmonic motion
voltage and current for ac curernts
root mean square
Vrms = sqrt(2)/2Vmax
Irms = sqrt(2)/2I max
magnetic field strength measured in….
units of tesla, T
static electric field produces ____ force on a magnet, static magnetic field produces ____ force on an electric charge
NO
changing an electric field induces a _____, and changing a magnetic field induces an _____
magnetic field, electric field
force on a charge moving through a magnetic field
F = qvBsin(theta) theta = angle between magnetic field and velocity of the charge
a charged particle moving through a magnetic field….
will be forced into a curved path
