930 likes | 1.08k Views
+ Q free on inner surface. + + + + + + + + + + + +. - - - - - - -. - q bound. Symmetry – fields must be uniform – field lines perpendicular to plates. + q bound. + + + + + +.
E N D
+Qfreeon inner surface + + + + + + + + + + + + - - - - - - - -qbound Symmetry – fields must be uniform – field lines perpendicular to plates +qbound + + + + + + - - - - - - - - - - - - -Qfreeon inner surface Interior points electric field must be zero
area of plates A + + + + + + + + + + + + +Qfreeon inner surface plate separationd -Qfreeon inner surface - - - - - - - - - - - -
+ + + + + conductor - - - dielectric Gauss’s Law
dielectric Constant (polar molecules) frequency
Fme dy + + + + + + + + + + + + + + + + + + F - - - - - - - - -
+ + + + + + + + + + + + - - - - - - - - + + + + + + + + - - - - - - - - - - - - Electric field Electric displacement Polarization
only some of the windings are shown A Integration paths B C
L Bz Bz dA1 dA2 Br dA3
Z Y X
Bz1 Br = 0 Ienclosed = 0 I A Bz2 s x
Bz1= 0 C Br = 0 Ienclosed = nsI I Bz2 s Ienclosed = 0 I Bz1= 0 Bz2 x x x x x x
single turn of wire with current I B around integration loop B dr = 0 and Br = 0 outside loop Bz = 0
iron core BFe HFe gap region Bgap Hgap i coil windings Bair Hair
. . . . . . . . 3 X X X X X X 2 Current i out of page Circulation loop: square of length L 1 4 Current i into page Cross-section through electromagnet
thickness t width L q = - e area A electrons are the charge carriers in copper
+ - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + -
+ + + + + + + + + dy + + + + + + + + + F - - - - - - - - - -q +q
C + + + + + + + + + V r CA CB - - - - - - - - - L-x C = CA + CB x
Induced dipole moment – helium atom +2e +2e -e -e -e -e Zero electric field – helium atom symmetric zero dipole moment A B effectively charge +2e at A and -2e at B dipole moment p = 2ed
Induced dipole moment – sulfur atom +16e +16e -8e -8e -8e -8e Zero electric field – helium atom symmetric zero dipole moment A B effectively charge +16e at A and -16e at B dipole moment p = 16ed
Er E P r2 r + (d/2)cos r1 r – (d/2)cos r (d/2)cos +q -q
dA +f + + + + + + + + + -b +b - - - - - - - - - -f
-q +q
S +f -b O r +b -f
Width of ring r d Radius of ring r sin + + + Area of the shaded ring between and + d surface S d r - Pcos - -
+ + + electric field at O due to charge dqe E0 cos E0 element of charge dqe - - -
+Ze +Ze d a a d << a
F F +Q d F - Q
+ p E U 0 - p E π π/2 0
U = - p E Lowest energy state U = 0 U = + p E highest energy state - - - = 90o + + + = 0 = 180o
r - 1 1/T
Po T
1 slope = 1/3 0 10 pE/kT
Gaussian surface S conducting sphere q air a r non-conducting liquid Symmetry field lines must be radial
conducting sphere q Eairt air Eliquidt non-conducting liquid Symmetry Eairt = Eliquidt Eair = Eliquid = E
field lines of E field lines of D +
field lines of D + + + + + + + + + + greater concentration of charge on surface bounded by liquid field lines of E +
- + + - - + + shift in atoms due to ionic nature of bond induced dipoles due to shift in electron cloud rotation orientation of polar molecules
6 5 4 S N HFe Hair Circulation loop: square side L 2 1 3
Cylindrical Gaussian surface Gauss’s Law for magnetism B-field lines – form continuous loops
N pole im Bound surface currents im (right hand screw rule)
un-magnetized piece of iron Bar magnet bought near un-magnetized piece of iron N N N Bar magnet will attract the iron that was initially un-magnetized north pole attracts south pole
Cu ramp Fe ramp plastic ramp N N N
Circulation loop for circulation integration used in applying Ampere’s Law N N Hair Hiron
B I I (0,0) d H B d
Miron PERMANENT MAGNET Hiron B B, Hgap Mgap = 0 B = Bgap = Biron ELECTROMAGNET Miron Hiron B Mgap = 0 B, Hgap B = Bgap = Biron
Y thickness t area A = wt width w X current in X direction Z magnetic field in Z direction Schematic diagram of a Hall Probe