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68 Cards in this Set

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What are the two forms of Coulomb's Law?
F= ke*qs*qf*r hat/r^2

F=ke*qs*qf*r vector/r^3
What is the relationship between potential energy and force?
U(x) = -∫ Fdx

F = -dU/dx
What is the equation for the potential energy of two point charges?
U(r)=ke*qs*qf/r
What changes occur to an object as it approaches the speed of light?
length contracts, mass increases, time slows down
What is the equation of a stub?
s=rh hat X l
What is the stub force proportional to?
the charge of the field particle, the thread density, and betaXs
What is the Lorentz force equation?
F=qfEs+qfvf X Bs
What are the equations for electric potential?
V=U/q
V(x) = -∫ Edx
How can you tell the direction of a field by it's field lines?
The direction is tangent to the line at a given point.
What are two ways of estimating the strength of a field?
Number of lines thru contour/area

number of contours thru line/length
What is the change in kinetic energy of a particle in an electric field?
DeltaK = -qDeltaV
What is the general motion of a charged particle in a uniform magnetic field?
a helical path
What is the equation for the cyclotron radius?
p=qBr
What two equations do we need to know to derive the cyclotron radius equation?
F=mv^2/r

F=qvB
What is the equation for a mass spectrometer radius?
(1/B)*(sqrt(2mDeltaV/q))
What is the general equation for current?
I=Delta q/Delta t
Relate an electron's circuit voltage to its potential energy?
U=qV
What are the three equations that have to do with resistors?
V=IR
P=IV
R=rho l/A
What is the potential energy of the earth?
0V
What is the charge on an object with respect to charge density?
q= ∫rho dV
What is dA for a square?
dA=L dx
What is dA for a disk?
dA=2 pi r dr
What is dV for a cylinder?
cut in little cylinders: dV=2 pi r L dr
cut into disks: dV=pi r^2 dz
What is dV for a sphere?
dV=4 pi r^2 dr
What is Gauss's Lavv of Electricity?
EA = 1/epsilon ∫rho dV
How many junction equation are there in a circuit?
One less than the number of junctions.
How many loop equations do you need to analyze a circuit?
# loop eq.=# currents-#junction eq.
What is the magnetic field of a long, current-carrying wire?
B= (mu0 i )/(2pi r)
What is the equation for charge and capacitance?
Q = CV
What is the equation for the electric field inside a capacitor?
E=V/d
What is the geneeral equation for capacitance?
C=epsilon0*A/d
What is the eq. for the energy stored in a capacitor?
U=.5*C*V^2
What is the equation for an RC time constant?
tao = RC
What is the eq. for Q in RC charging?
Q(t)= Q(f)*(1-exp(-t/tao))
What is the eq. for an electric field inside a spherically symmetric charge distribution?
E= Qenc/(4*pi*epsilon0*r^2)
Give 2 practical expression for flux.
flux = field*area
Flux=EA=qenc/epsilon0
What is the eq. for a line intergal?
A=Bl=mu0*ienc
What is the Biot-Savart law?
B=(mu0*i/4*pi)∫(dlXR)/R^3
What is the eq. for the force on a segment of current carrying wire?
F= iLXB
What is the equation for the magnetic dipole moment of a current loop?
mu=iA, where A is the direction of your thumb when your fingers wrap in the direction of the current.
What is the torque on a magnetic dipole in a magnetic field?
tao=muXB
What is the potential energy of a magnetic dipole in a magnetic field?
U=<-mu, B>
What is the torque on an electric dipole in an electric field?
tao=pXE
What is the potential energy of an electric dipole in an electric field?
U=<-p, E>
What is the magnetic susceptibility?
Bint=chi Bext
The electric and magnetic fields of accelerating charges fall of as what with respect to r?
1/ r rather than 1/ r ^2
How are the directions of E, B and r related for an accelerating charge?
EXB=r
How do you find the E of an accelerating point charge?
E=rX(rXa)
How do you find the B of an accelerating point charge?
B= rXE
How are the magnitudes of the electric and magnetic fields are related?
E=cB
If current increases or decreases in a wire, an induced electric field points _____ the acceleration.
opposite
What is displacement current?
hypothetical current that would give rise to the magnetic fields between capacitors.
What is the equation for displacement current?
i dis = mu0 epsilon0 dflux/dt
Define inductance.
V=-Ldi/dt
What is eq. for the energy stored in an inductor?
U=.5Li^2
What is the LR time constant?
tao=L/R
What is the angular freq. of an LC circuit?q
omega=1/(LC)^(1/2)
What is the impedance for series LRC circuits?
Z=((Xl-Xc)^2 +R^2)^(1/2)
What is Xl?
Xl=omegaL
What is Xc?
Xc=1/(omegaC)
What is the eq. for freq. in and LRC circuit?
f=omega/(2pi)
How do you find theta in an LRC circuit?
tan(theta)=(Xl-Xc)/R
What colors represent hot wiring?
black and red or black tape
What colors represent neutral wiring?
white
What colors represent grounded wiring?
green and bare
What are the advantages/disadvantages of copper vs. aluminum?
copper is better
aluminum is cheaper
Which slot is hot in an outlet?
short
What's the wavenumber?
k=2pi/lambda