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， 如果看一下基本自由空间介电常，那么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电荷除以真空介电常。

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，这个方程表明电通量是表面积上电场一个组成部分，它等于闭合电荷除以自由空间介电常。

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：低介电常和低耗散因，大限度地减少信号损失。

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重建介电常分布和URT重建声速分布。

This is the permittivity of free space.

这是自由空间介电常。

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

还知道库仑常等于四π乘以真空介电常倒。

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.

您以使用能量密度方程，并用电场和介电常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用于重建横截面介电常分布, 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.

通过与正点电荷同心球面电通量等于正点电荷电量除以自由空间介电常。

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常方程，电场自由空间介电常 epsilon 为零，磁场自由空间介电常 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.

得出结论，由无限大薄充电平面产生电场大小等于面电荷密度除以两倍自由空间介电常。

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.

如果你不提不会怪你，但自由空间介电常是之前使用相对论常，它将电荷与电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.

这等于电通量随时间变化乘以自由空间常介电常。