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68 Cards in this Set
- Front
- Back
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What are the two forms of Coulomb's Law?
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F= ke*qs*qf*r hat/r^2
F=ke*qs*qf*r vector/r^3 |
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What is the relationship between potential energy and force?
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U(x) = -∫ Fdx
F = -dU/dx |
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What is the equation for the potential energy of two point charges?
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U(r)=ke*qs*qf/r
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What changes occur to an object as it approaches the speed of light?
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length contracts, mass increases, time slows down
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What is the equation of a stub?
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s=rh hat X l
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What is the stub force proportional to?
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the charge of the field particle, the thread density, and betaXs
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What is the Lorentz force equation?
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F=qfEs+qfvf X Bs
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What are the equations for electric potential?
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V=U/q
V(x) = -∫ Edx |
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How can you tell the direction of a field by it's field lines?
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The direction is tangent to the line at a given point.
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What are two ways of estimating the strength of a field?
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Number of lines thru contour/area
number of contours thru line/length |
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What is the change in kinetic energy of a particle in an electric field?
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DeltaK = -qDeltaV
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What is the general motion of a charged particle in a uniform magnetic field?
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a helical path
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What is the equation for the cyclotron radius?
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p=qBr
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What two equations do we need to know to derive the cyclotron radius equation?
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F=mv^2/r
F=qvB |
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What is the equation for a mass spectrometer radius?
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(1/B)*(sqrt(2mDeltaV/q))
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What is the general equation for current?
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I=Delta q/Delta t
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Relate an electron's circuit voltage to its potential energy?
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U=qV
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What are the three equations that have to do with resistors?
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V=IR
P=IV R=rho l/A |
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What is the potential energy of the earth?
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0V
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What is the charge on an object with respect to charge density?
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q= ∫rho dV
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What is dA for a square?
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dA=L dx
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What is dA for a disk?
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dA=2 pi r dr
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What is dV for a cylinder?
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cut in little cylinders: dV=2 pi r L dr
cut into disks: dV=pi r^2 dz |
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What is dV for a sphere?
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dV=4 pi r^2 dr
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What is Gauss's Lavv of Electricity?
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EA = 1/epsilon ∫rho dV
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How many junction equation are there in a circuit?
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One less than the number of junctions.
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How many loop equations do you need to analyze a circuit?
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# loop eq.=# currents-#junction eq.
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What is the magnetic field of a long, current-carrying wire?
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B= (mu0 i )/(2pi r)
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What is the equation for charge and capacitance?
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Q = CV
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What is the equation for the electric field inside a capacitor?
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E=V/d
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What is the geneeral equation for capacitance?
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C=epsilon0*A/d
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What is the eq. for the energy stored in a capacitor?
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U=.5*C*V^2
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What is the equation for an RC time constant?
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tao = RC
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What is the eq. for Q in RC charging?
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Q(t)= Q(f)*(1-exp(-t/tao))
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What is the eq. for an electric field inside a spherically symmetric charge distribution?
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E= Qenc/(4*pi*epsilon0*r^2)
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Give 2 practical expression for flux.
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flux = field*area
Flux=EA=qenc/epsilon0 |
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What is the eq. for a line intergal?
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A=Bl=mu0*ienc
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What is the Biot-Savart law?
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B=(mu0*i/4*pi)∫(dlXR)/R^3
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What is the eq. for the force on a segment of current carrying wire?
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F= iLXB
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What is the equation for the magnetic dipole moment of a current loop?
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mu=iA, where A is the direction of your thumb when your fingers wrap in the direction of the current.
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What is the torque on a magnetic dipole in a magnetic field?
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tao=muXB
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What is the potential energy of a magnetic dipole in a magnetic field?
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U=<-mu, B>
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What is the torque on an electric dipole in an electric field?
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tao=pXE
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What is the potential energy of an electric dipole in an electric field?
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U=<-p, E>
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What is the magnetic susceptibility?
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Bint=chi Bext
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The electric and magnetic fields of accelerating charges fall of as what with respect to r?
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1/ r rather than 1/ r ^2
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How are the directions of E, B and r related for an accelerating charge?
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EXB=r
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How do you find the E of an accelerating point charge?
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E=rX(rXa)
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How do you find the B of an accelerating point charge?
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B= rXE
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How are the magnitudes of the electric and magnetic fields are related?
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E=cB
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If current increases or decreases in a wire, an induced electric field points _____ the acceleration.
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opposite
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What is displacement current?
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hypothetical current that would give rise to the magnetic fields between capacitors.
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What is the equation for displacement current?
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i dis = mu0 epsilon0 dflux/dt
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Define inductance.
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V=-Ldi/dt
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What is eq. for the energy stored in an inductor?
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U=.5Li^2
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What is the LR time constant?
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tao=L/R
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What is the angular freq. of an LC circuit?q
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omega=1/(LC)^(1/2)
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What is the impedance for series LRC circuits?
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Z=((Xl-Xc)^2 +R^2)^(1/2)
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What is Xl?
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Xl=omegaL
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What is Xc?
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Xc=1/(omegaC)
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What is the eq. for freq. in and LRC circuit?
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f=omega/(2pi)
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How do you find theta in an LRC circuit?
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tan(theta)=(Xl-Xc)/R
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What colors represent hot wiring?
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black and red or black tape
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What colors represent neutral wiring?
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white
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What colors represent grounded wiring?
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green and bare
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What are the advantages/disadvantages of copper vs. aluminum?
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copper is better
aluminum is cheaper |
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Which slot is hot in an outlet?
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short
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What's the wavenumber?
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k=2pi/lambda
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