10 Magnetism of Matter 磁 性Electromagnetic Waves 電磁波

How can a clay-walled kiln reveal Earth’s magnetic field of the past?

10-2.7 Find B(r)

R)r(for 2

)(2

R)r(for 2

)(2

200

200

200

00

200

200

00

dtdE

rRB

dtdERER

dtdrB

dtdErB

dtdErEr

dtdrB

dtdsdB E

10-2.8 Displacement Current

0 0 0

0

0 , 0

+

+

Eenc

Ed

d enc enc

dB ds idt

didt

B ds i i

10-2.9 Maxwell’s Equations

10-3 Electromagnetic Waves

The oscillating E and B FieldsA Most Curious Wave –The ether ( 以太 )

)sin()sin(tkxBBtkxEE

m

m

34-3 The Traveling Electromagnetic Wave

hdE

EhhdEEsdEdtdsdE

)(

• The induced electric field:

dtdB

dxdE

dtdBhdxhdE

dtdBhdx

dtdhdxB B

B

,

),)((

hdE

EhhdEEsdEdtdsdE

)(

cBE

tkxBtkxkE

tkxBtB

tkxkExE

tB

xE

dtdB

dxdE

m

m

mm

m

m

)cos()cos(

)cos(

)cos(

․The induced magnetic field:

hdB

BhhdBBsdBdtdsdB E

)(

00

000000

00

0000

1c ,1)/(

1)cos()cos(

)(

),)((

ckBE

tkxkxkBtE

tB

dtdEhdxhdB

dtdEhdx

dtdhdxE

m

m

m

EE

10-3.3.1 Radiation Pressure․ Momentum Gain of an Object

)reflection (total 2

)absorption (total

cUp

cUp

Momentum change

energy change

․The Force Exerted by Radiation

)reflection (total 2 2

)absorption (total

cIp

cIAF

cIp

cIAF

ctIA

cUptIAU

tpF

r

r

mGMcPRFF

rRGM

rmGMF

crRP

cRIF

cIAF

rPI

S

Sgr

SSg

Sr

rS

7

2

3

2

2

22

2

107.116

33

44

4

․The size of comet particles