ㄜ~~你
在幹麻~
※ 引述《Hydrisk (莎莉絲)》之銘言：
: Poyntiny's Theorem
: We = ε/2 (E‧E)
: Wm = 1/2μ(B‧B)
: Uem = 1/2(ε(E‧E) + 1/μ(B‧B))
: Uem is called energy density
: Accroding to the Lorentz force law
: F‧dl = q(E + V ×B)‧Vdt
: magnetic forces do no work
: F‧dl = qE‧Vdt
: q = ρdτ
: F‧dl = E‧ρVdτdt
: dW/dt = ∫(E‧J)dτ
: Accroding to the Ampere's law with Maxwell's equation correction
: ▽ ×B = μJ+εμ(dE/dt)
: J = 1/μ(▽ ×B) － ε(dE/dt)
: => dW/dt = ∫(1/μE‧(▽ ×B) － εE‧(dE/dt))dτ
: E‧(▽ ×B) = B‧(▽ ×E) － ▽‧(E ×B)
: Accroding to the Faraday's law
: ▽ ×E = －(dB/dt)
: => E‧(▽ ×B) = －B‧(dB/dt) － ▽‧(E ×B)
: dW/dt = ∫(－1/μB‧(dB/dt) － εE‧(dE/dt))dτ － 1/μ▽‧(E ×B))dτ
: B‧(dB/dt) = 1/2(d(B‧B)/dt) E‧(dE/dt) = 1/2(d(E‧E)/dt)
: dW/dt = (d/dt)(－1/2)∫(ε(E‧E) + 1/μ(B‧B))dτ － 1/μ∮(E ×B)‧da
: Poynting's vector S = 1/μ(E ×B)
: The first integral on the right is the tatle energy in the electromagnetic
: field.While the sencond integral is the energy flow on boundary surface of
: the volume V.
--
我給妳的愛寫在西元前~
深埋在美索不達米亞平原~
--
※ 發信站: 批踢踢實業坊(ptt.csie.ntu.edu.tw)
◆ From: 218.166.105.55