So, instead of having the periodic variation of water, or the periodic variation of air density here we're talking about an electric field.

不像水或者空气密度的,周期变化，我们这里,讨论的是电场。

麻省理工公开课 - 化学原理课程节选

The electric current density possible with such windings is approximately 30 to 100 times greater than the values achievable with copper coils at room temperature.

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Plus, according to Andy Chu, vice president of marketing and communications at battery-maker A123, because hybrids do not rely solely on electric, they can afford to sacrifice some energy density and stick with the NiMH without fear of running out of juice.

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Bosch reckons that for electric cars to become universally popular, a threefold increase in energy density and a fall of two-thirds in the price of batteries will be needed.

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