In the lab frame the total linear charge density of a current-carrying wire must be zero and while in the rest frame of the electrons making up the current the total volume charge density must be zero .

在实验室坐标系中，载流中性导线的总体电荷线密度必然是零，同时在与形成电流的电子相对静止坐标系中总的 电荷 体 密度必然为零。

The volume charge density of the powder emulsion explosives is up to - 2.62 × 10-6C / kg by the result of airflow conveying experiment .

在气流输送试验中，粉状乳化炸药的质量 电量 密度达-2.62×10~（-6）C/kg。

It can estimate the detonation velocity of industrial explosive more accurately than the conventional volume addition formula at different formula and charge density or at the same formula charge density and different temperature of explosive .

与传统的爆速 体积加和公式比较，该模型能更准确地估算工业炸药在不同配方、不同 装 药 密度下，或者在同一配方、相同装药密度、不同药温时的爆速。