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46 Cards in this Set
- Front
- Back
volts =
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Q (charge)/ C
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dot product/scalar product
A dot B |
AxBx + AyBy + AzBz
ABcosθ |
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vector/cross product
A cross B |
(AyBz-AzBy)i + (AzBx-AxBz)j + (AxBy-AyBx)k
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gradient
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vector field that points in the direction of greatest increase, dot product of (Function) and (d/dx, d/dy, d/dz)
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symbol for gradient
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down side up triangle
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Flux
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surface intergal of a vector dot product da (infinitesimal surface which is normal to the surface)
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zero divergence
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soleniod
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Coulombs Law
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F=kQq/r^2
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E field intensity related to charge
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E=F/Q
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Electrostatic field is
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conservative
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Electric Potential
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potential energy per unit charge, usually measured in volts
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electric dipole moment
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point from negative charge to positive chargem
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magnetic dipole moment
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point through the loop with a magnitude equal to the current in the loop times the area of the loop
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electric dipole moment
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F=Kq/r^2
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total charge
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intergal of charge density with repect to area
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in static equibrium, macroscopic electric field inside a conductor
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is zero
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induced charges
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charges appearing on surface of material due to the presence of external field
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Gauss Law
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prove field outside an isolated and spherically symmetrical charged ion is exactly the same as it all its charge were concentrated at the center
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flux =
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E*area*cos, can be an intergal
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Dipolar Polarisability
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usually fluids, water, one end of molecule is slightly positive, 1 slightly negative, charges are equal and opposite, In an E fild, force will act on the charge, forces are opposite, so no net force but there is torque P=qa(distance)-dipole moment,
T=pxE=axq.E, a is distance between two charges |
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Ionic Polarisability
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salt, ions, if a field is applied going to the right, postive charges move to the right and negative charges move to the left, this will lengthen some dipole moments, and shorten other, giving a net effect
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Atomic Polarisability
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Cloud of electrons move aways from field, creating a dipole moment
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Polorization is the total dipole moment, divided by volume
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associated with displacement of charges
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Capasitors
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store charge, the more charge, the better capasitor
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Increase dielectric constant
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to have a higher capastitance
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For air, dielectric constant
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approximately 1
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Uniquness theorum
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Solution of Laplace equation is unique if boundry equation givens
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Current (moving charges) feels a force in the presence of another current
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or permiabbly magnetic materials (related to permanent microscopic currents) Magnetic fields just a convience to define these forces
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no magnetic
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monopoles!!!
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Ferromagnetic
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Fe, Ni, increases field when put in field
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Diamagentic
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10^-5 effect on field/glass
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Paramagentic
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10^-5 decrease on field
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In a magnetic field, a diamagnetic material and paramagnetic
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forms dipole moments in opposition to field. In paramagnet have constant dipole, stronger than induced, so attracted
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Magnetisation
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magnitude of dipole moment in direction of field X N
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Nuclear magnetization
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can neglect
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most atoms in isolation have magnetic moments
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as they have total angular momentum non-zero
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In solids, filled shells lead to magnetic
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moments
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In Fe, Ni, in unfilled shells
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momentum is non zero, permant magnetic dipole moments
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magnetic dipole=0
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for all diamagetic in no field
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Average induced dipole moment
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This is for all electrons in atom, Can now get magetization, which is just Nxaverage induced dipole moment.
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Paramagentision
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Orientation of dipole moments in no field is random. In a B field, these moments will align with field. Field will induce moments, but their effect is less than that of a permanent dipole
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Curie Temperature
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below this temp, spins are alinged in domains. Result of strong interaction between free electrons and lattice electrons, need quatum, so not explained
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change in magnetic field
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cause current, electromagnetic induction
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magnet approach wire
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current was induced, induced current always opposes change in magnetic field, Lenz rule
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Induced current
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means induced electric field
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the faster the wire loop moves
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the greater the current
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