定义

电磁波 (n=1)

\((\nabla_{L} \times)^n E = \frac{-\partial B}{\partial t}\) 量纲： \([V/m^{n+1}]\)
\((\nabla_{L} \times)^n B = \mu_0 J(J=0) + \mu_0 \varepsilon_0 \frac{\partial E}{\partial t}\) 量纲： \([T/m^{n+1}]\)
\(E_0B_0…E_\infty B_\infty\) 交变E产生交变B，交变B产生交变E，实验中，可以测量 0V 时间间隙（因为E交变）\(\Delta t\)，\(f=1/2\Delta t\), 就得到电磁波（也可以叫做，交流电）的频率。

可见光是 特定频率的电磁波，你的眼睛只是天线：

\((\nabla_{L} \times) ((\nabla_{L} \times)^n E) = \frac{-\partial }{\partial t} ((\nabla_{L} \times)^n B) = \frac{-\partial }{\partial t} (\mu_0 J + \mu_0 \varepsilon_0 \frac{\partial E}{\partial t})\)

电流 J = 0.

\((\nabla_{L} \times) ((\nabla_{L} \times)^n E) = \frac{-\partial }{\partial t} (\mu_0 \varepsilon_0 \frac{\partial E}{\partial t})\)

对比波动方程, \(\nabla \times (\nabla \times E) = \nabla(\nabla \cdot E) - \nabla^2E\), 和 \(\nabla \cdot E = 0\)(vaccum and no free charge)：

\(\nabla_L^2 \psi=\frac{1}{v^2}\nabla_T^2 \psi\)

\(\nabla_{L}^2 E = \frac{\partial }{\partial t} (\mu_0 \varepsilon_0 \frac{\partial E}{\partial t})\)

so \(v = 1/\sqrt{\mu_0 \varepsilon_0}\)

\(\mu_0 \varepsilon_0\) 真空 电导常数, 磁导常数 实验可测，对比发现和测到的光速一致。

透明: Transparent(NOT Transmission) 指的是 特定频率的电磁波 不与材料共振(吸收和反射很弱)。

镜面指的是 特定频率的电磁波 吸收很弱，镜面反射很强

白色指的是 特定频率的电磁波 吸收很弱，漫反射散射都很强，对可见光波段均匀

Electromagnetic Waves (n=1)

\(\nabla_{L^n} \times E = \frac{-\partial B}{\partial t}\) Dimension: \([V/m^{n+1}]\)

\(\nabla_{L^n} \times B = \mu_0 J(J=0) + \mu_0 \varepsilon_0 \frac{\partial E}{\partial t}\) Dimension: \([T/m^{n+1}]\)

\(E_0B_0…E_\infty B_\infty\) Alternating E produces alternating B; alternating B produces alternating E. In experiments, one can measure the time gap between 0V points (because E alternates) \(\Delta t\), then \(f=1/2\Delta t\), and thus obtain the frequency of the electromagnetic wave (which can also be called alternating current).

Visible light is an electromagnetic wave of a specific frequency; your eye is just an antenna:

\(\nabla_{L^n} \times (\nabla_{L^n} \times E) = \frac{-\partial }{\partial t} (\nabla_{L^n} \times B) = \frac{-\partial }{\partial t} (\mu_0 J + \mu_0 \varepsilon_0 \frac{\partial E}{\partial t})\)

Current J = 0.

\(\nabla_{L^n} \times (\nabla_{L^n} \times E) = \frac{-\partial }{\partial t} (\mu_0 \varepsilon_0 \frac{\partial E}{\partial t})\)

Comparing with the wave equation, \(\nabla \times (\nabla \times E) = \nabla(\nabla \cdot E) - \nabla^2E\), and \(\nabla \cdot E = 0\) (vacuum and no free charge):

\(\nabla_L^2 \psi=\frac{1}{v^2}\nabla_T^2 \psi\)

\(\nabla_{L^n}^2 E = \frac{\partial }{\partial t} (\mu_0 \varepsilon_0 \frac{\partial E}{\partial t})\)

so \(v = 1/\sqrt{\mu_0 \varepsilon_0}\)

\(\mu_0 \varepsilon_0\) — vacuum permittivity and permeability constants, experimentally measurable; comparison shows agreement with the measured speed of light.

Transparent (NOT Transmission) means that electromagnetic waves of a specific frequency do not resonate with the material (absorption and reflection are very weak).

要求中文 可发邮件。sorry, but author is at school.