ch 5 - Electrostatics and Magnetism Flashcards Preview

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Flashcards in ch 5 - Electrostatics and Magnetism Deck (20)
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electrical potential of dipole

V=(kq)/rsub1 - (kq)/rsub2 = (kq(rsub2 - rsub1))/rsub1rsub2
At greater distance: V = ((kqd)/rsquared) x costheta;

d = distance between +q and -q (source charges); rsub1 = distance between the chosen point in space and +q; rsub2 = distance between said point and -q


dipole moment (p)

SI units are C x m: p = qd


perpendicular bisector of the dipole

plane that lies halfway between +q and -q. Because the angle between this plane and the dipole axis is 90 degrees (and cos 90 = 0) the electrical potential at any point along this plane is 0.


electric dipole

result of two equal and opposite charges being separated a small distance (d) from each other; can be transient or permanent


magnitude of the electric field on the perpendicular bisector of the dipole

E = 1/(4pi x epsilonsub0) x p/r^3


electrostatic constant (k)

8.99 x 10^9 (N x m^2)/C^2


net torque on dipole

T = pE sintheta where p = magnitude of dipole moment (p = qd), E = magnitude of uniform external electric field, and theta = angle the dipole moment makes with the electric field; this will cause dipole to reorient itself so that its dipole moment (p) aligns with the electric field E


equipotential lines

lines on which the potential at every point is the same; potential difference bt any two points on an equipotential line is zero


SI unit for magnetic field strength

tesla (T) 1 T = 1 (N x s)/(m x C); or when smaller measured in gauss. 10^4 gauss = 1 T


diamagnetic materials

made of atoms with no unpaired electrons and that have no net magnetic field; can be called weakly antimagnetic


Paramagnetic materials

have unpaired electrons; weakly magnetized in the presence of an external magnetic field, aligning the magnetic dipoles of the material with the external field (ex aluminum, copper and gold)


Ferromagnetic materials

have unpaired electrons and permanent atomic magnetic dipoles that are normally oriented randomly so that the material has no net magnetic dipole. will become strongly magnetized when exposed to a magnetic field or under certain temps (iron, nickel and cobalt)


for infinitely long and straight current-carrying wire, equation for magnitude of magnetic field

B = (fancy u sub 0 x I)/(2pi r) I (i) = current in the wire; r = perpendicular distance of the current from the wire; B = magnetic field; fancy u sub 0 = permeability of free space (4pi x 10^-7 (T x m)/A)


right hand rule for straight wire magnetic fields

point thumb in direction of current and wrap fingers around current-carrying wire. Fingers mimic circular field lines curling around wire


magnitude of magnetic field at center of circular loop of current carrying wire

B = (fancy u sub 0 x I)/2r r = radius of loop; fancy u sub 0 = permeability of free space (4pi x 10^-7 (T x m)/A); B = magnetic field; I = current in wire


Lorentz force

sum of the electrostatic and magnetic forces acting on charges in magnetic field


magnetic force

F sub B = qvB sin theta; q = the charge; v = magnitude of velocity, B = magnitude of magnetic field; theta = smallest angle between the velocity vector v and the magnetic field vector B; unit is N


right-hand rule of magnetic forces

to determine direction of the magnetic force on moving charge; position right thumb in direction of the velocity vector; put fingers in direction of magnetic field lines; palm points in the direction of the force vector for a positive charge, while back points in direction of force vector a negative charge


For a straight wire, magnitude of force created by external magnetic field

F sub B = ILB sin theta; I (i)= current; L = length of wire in the field; B = magnitude of magnetic field; theta = angle between L and B


fancy uC = how many coulomb?

1 x 10^-6 C