Comunicazione elettriche - i campi elettromagnetici

[ ]

E ( r , t ) V m

[ ]

H ( r , t ) A m

[ ] =

Cb A sec

D ( r , t ) 2

Cb m

[ ] =

B ( r , t ) Wb V sec

2

Wb m

∆ ρ

Q (

t ) Cb ≡

Q (

t ) ( r , t ) dv

ρ =

( r , t ) lim

∆ ∆

V 0 3

V m V [ ]

A = ⋅ ⋅

ˆ

( ) ( , )

I t J r t n ds A

J ( r , t ) 2

m S

Φ = ⋅ ⋅

ˆ

A n ds

S

∂ { }

∇ × + =

E ( r , t ) B ( r , t ) 0

∂

t

∂ ! "

{ }

∇ × − =

H ( r , t ) D ( r , t ) J ( r , t )

∂

t ρ

∂ ( r , t )

∇ ⋅ = −

J ( r , t ) ∂

t

d

⋅ = − ⋅ ⋅

ˆ

E dl B n ds

dt

C S

d ! "

⋅ − ⋅ ⋅ =

ˆ

H dl D n ds I (

t )

dt

C S d ρ

⋅ ⋅ = −

ˆ

J ( r , t ) n ds ( r , t ) dv

dt

S V

# $ ⋅ ⋅ = ∇ ⋅

ˆ

A n ds A

dv

S V

( )

∇ ⋅ ∇ × =

A 0

% !

# % & ⋅ = ∇ × ⋅ ⋅

ˆ

A dl A n ds

C S

# δ − =

f ( x ) ( x x ) dx f ( x )

0 0

x ∆ →

# S 0

⋅ ⋅ =

ˆ

A n ds 0 A discontinu o

∆

S 1

' ρ

∇ ⋅ = ∇ ⋅ =

D ( r , t ) ( r , t ) B ( r , t ) 0

⋅ ⋅ = ⋅ ⋅ =

ˆ ˆ

D ( r , t ) n ds Q (

t ) B ( r , t ) n ds 0

S S

( $

ε µ

= = = + = +

D E B H D D P B B M

0 0

[ ] F

{ }

+∞ +∞ =

= ⋅

D ( r , t ) dt ' dr ' ( r , r ' ; t , t ' ) E ( r ' , t ' ) 4

m sec

e

e

− ∞ − ∞ % $

) { }

+∞

= ⋅

D ( r , t ) dr ' ( r , r ' ; t ) E ( r ' , t )

# $ e

− ∞

* { }

+∞

) = ⋅

D ( r , t ) dt ' ( r ; t , t ' ) E ( r , t ' )

% $ e

( − ∞

# + # ,%

τ τ

= −

(

t , ) (

t )

% # e e

0 ρ ρ

= −

( r , ) ( r )

% e e

-+ .

.

ε

= ⋅

D ( r , t ) ( r , t ) E ( r , t )

0 /+

1 + 2 + 3 ε

=

# ( r , t ) ( r , t )

e

( •

0 ε ε ε ε

• = = = ( r , t )

xx yy zz

! ε

=

D ( r , t ) E ( r , t ) 1 ,0 3

σ = ↔ =

0 J 0

$ c −

r r '<