And so if we look at basic free space permittivity, so what we would have in the middle now is going to be just a vacuum.

因此， 如果我们看一下基本自由空间介，那么我们现在中间将只是一个真空。

And that  all still equals the charge inside the Gaussian surface divided by the permittivity of free space.

这仍然等于高斯面内荷除以真空介。

Mathematically, this equation says that electric flux is the integral of the electric field over the area of the surface, which is equal to the enclosed charge, divided by the permittivity of free space.

在学上，这个方程表明通量是表面积上场一个组成部分，它等于闭合荷除以自由空间介。

29. Question: What is the key factor to consider when choosing a PCB material for high - frequency applications in PCBA? Answer: Low dielectric constant and low dissipation factor to minimize signal loss.

29. 问题：为 PCBA 中高频应用选择 PCB 材料时要考虑关键因素是什么？答案：低介和低耗散因，可最大限少信号损失。

The permittivity distribution reconstructed by ECT and sound velocity distribution reconstructed by URT are processed by pixel-to-pixel thresholding fusion method.

通过像素阈值融合方法处理ECT重建介分布和URT重建声速分布。

This is the permittivity of free space.

这是自由空间介。

We also know the Coulomb constant equals the  inverse of the quantity four pi times the permittivity of free space.

我们还知道库仑等于四π乘以真空介倒。

You can take our energy density equation and substitute the magnetic field magnitude, B, with the electric field, times the square root of the permittivity constants.

您可以使用我们能量密方程，并用场和介平方根时间替换磁场大小 B。

ECT can be used to reconstruct the permittivity distributions of the cross section, while UT is skilled to distinguish the boundaries of two-phase.

ECT可用于重建横截面介分布, 而UT擅长区分两相边界。

The electric flux which passes through a sphere which is  concentric to a positive point charge equals the charge of the positive point charge  divided by the permittivity of free space.

通过与正点荷同心球面通量等于正点荷量除以自由空间介。

This equation simplifies down to an equation with two constants, the permittivity of free space for electric fields, epsilon naught, and the permittivity of free space for magnetic fields, mu naught.

该方程简化了具有两个方程，场自由空间介 epsilon 为零，磁场自由空间介 mu。

And we get that the magnitude of the electric  field which surrounds and is caused by an infinitely large, thin plane of charges  equals surface charge density divided by the quantity two times permittivity of free space.

我们得出结论，由无限大薄充平面产生场大小等于面荷密除以两倍自由空间介。

I won't blame you if you don't remember, but the permittivity of free space is a constant of proportionally we've used before, that relates electric charge to the physical effect of electric fields.

如果你不提我不会怪你，但自由空间介是我们之前使用相对论，它将荷与场物理效应联系起来。

And that is equal to the change in electric flux over time, multiplied by the permittivity of free space constant.

这等于通量随时间变化乘以自由空间介。