Upload
teerapong-onogk
View
15
Download
0
Embed Size (px)
DESCRIPTION
physics
Citation preview
- 1
1
(Electromagnetic Waves)
1.1 4
1 0
=
0 = 0
0 (1-1)
2
= = = (1-2) 3
=
=
(1-3)
4 - 0 00
x y z x yz
E B ( 1-3 ) ( 1-4) ( Q 0 i 0 ) ( 1-3 ) (1-4 )
1-1 = 00
(1-5)
= 0 + 00
= 0 + 00
(1-4)
- 2
(1-3 ) (1-5)
Ex
B
t
(1-6)
- Bx
0 0
E
t
(1-7)
(1-6) (1-7)
2
0 02
E B E
x x t t t
2
2 = 00
2
2
1-2
1.2
2 2
0 02 2
E E
x t
(1-8)
2 2
0 02 2
B B
x t
(1-9)
= (sin ( ) (1-10) = (sin ( ) (1-11)
k (Wave Number) = 2
, , = 2
- 3
() (Transverse Wave)
1-3
1.3
2 2
2 2 2
1y y
x c t
(1-12)
c c
0 0
1c
(1-13)
c Permittivity Permeability 7
0 4 10 /Tm A
12 2 2
0 8.85418 10 /C Nm
82.99792 10 /c m s
= (sin ( ) = (sin ( )
(1-6) (1-7)
E cB (1-14)
( ) ( ) ( )
( ) ( ) 90 ( ) 1.4
- 4
1-4 E
B (transverse wave)
1-5 x t
- 5
1-1 40.0 MHz +x 9-8 750 N/C y
) ) 750 N/C y )
1-6 1
) c f
cf
8
6
3.00 10
40.0 10
7.50 m
1f
6
1
40.0 10 82.5 10 s
) 750 N/C y
oB 0
E
c
8
750
3.0 10
N/Cm/s
62.5 10 T
)
2 f 78 10 s-1
k 2 / 0.838 rad/m
E 0 cos( )E kx t 7
750 0.838 8 10cos( )x t
B 0 cos( )B kx t 6 7
2.5 10 0.838 8 10cos( )x t
1.4
. 1888 LC
- 6
1-7 LC 1( / )LC
1-8 A B A G S
- B B
1-8
D
- 7
1- 9
G D G 1-4 D G
D B G 10 8 G G (1-4) D D G 1.5 7
- 8
1-10 1.6
1 1-11
1-11 1.7
(Intensity) Poynting Vector
0
1S E B
(1-15)
- 9
E B
0
1S E B
(1-16)
2
0 0 0
1 1 1E EEB E
c c (1-17)
= 2
0 (1-18)
= 2
0 (1-19)
1-12 Poynting Vector
1-12
1-13
p = U/c P = 2S/c
6 25 10 /N m
- 10
S S S I
2 2 200 0
1 1sin ( )I S E E kx t
c c
2sin ( )kx t 2sin ( )kx t 1 12
0 0E cB
2
0 0 0
0 0
1
2 2
1I S E E B
c (1-20)
root-mean-square rmsE 0 2/rmsE E (1-17)
20 0
1 1rms rms rmsI S E E B
c (1-21)
=
2
0
1-2 10 m 3.0 V / m
) ) )
) 800 8
3.01.0 10
3.0 10
EB
c
T
V/mm/s
) 2 2
0
8 7
0
3.0
2 2(3.0 10 4 10
( )
( )
EI
c
V/mm/s) T.m/A
21.2 10 2W/m
- 11
)
1-14 S r 2 2 24 4 10 1.2 10( ) ( )P r I 2m W/m 15.1 W
1 : 20 Emax = 0.200 (a) (b) (c)
1-8
1-15
- 12
( v ) ( f ) ( ) v f . (1-22) (spectrum) 1. - 2-3 Hz 109 Hz AM ( Amplitude Modulation) 530 KHz 1600 KHz FM (Frequency Modulation) 88 MHz 108 MHz - 2. (Microwave) 1 30 109 Hz 3 1011 Hz (RADAR, Radio Detection and Ranging)
3. (Infrared Wave) 1 7 10-7 3 1011 Hz 4 1014 Hz 4. (Visible light) 4,000 7,000 oA (1 oA 10-10m ) 4 1014 Hz 8 1014 Hz 5.6 10-7 m
- 13
1-1
(10-7 m) (1014Hz) 3.90 - 4.55 7.69 - 6.59 4.55 - 4.92 6.59 - 6.10 4.92 - 5.77 6.10 - 5.20 5.77 - 5.97 5.20 - 5.03 5.97 - 6.22 5.03 - 4.82 6.22 - 7.80 4.82 - 3.84
5. (Ultraviolet light) 60 nm 380 nm 8 104 Hz 3 1017 Hz (Ozone, O3) 6. (X-rays) 10-4 nm 10 nm 3 1017 Hz 5 1019 Hz
7. (Gamma rays) 10-10 m 10-14 m 3 1018 Hz 3 1032 Hz
- 14
1-16
1-9
(Morse code) (carrier wave ) (modulation) (demdulation)
(Morse code) (detector) (teletype)
- 15
2 (amplitude modulation) (AM) (frequency modulation) ( FM) 1-17
1-17
(scanning) 2 (pulse modulation) (pulse)
- 16
- 17
1. 5.4 x 10-7 T
) [ 162 N/C ] ) 0.8 c [ 130 N/C ]
2. SI 7100 1.00 10sin( )yE x t
) [ 333 nT ] ) [ 628 nm ] ) [ 4.77 x 104 Hz]
3. 5.0 250 kW [ 307 W/m2] 4. 0.2 V/m 20 km
[ 66.7 kW] 5.
300 ?
6. 900 kHz
50 [ 333 m, 9-00 x 105 Hz ] 7.