ON POTENTIAL
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as oil, glass, mica or paper, it is times smaller. This means that to bring a unit of positive charge to our sphere through such a medium takes times less energy than to bring it through air. In other words, to obtain the same charge an e.m.f. times smaller is sufficient, or, if the e.m.f. is the same, the resulting charge will be times larger. Hence by using a dielectric other than air the capacity of our condenser is increased times. The following table gives the value of for some dielectric materials—
Values of the Specific Inductive Capacity K in the C.G.S. Electrostatic System
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Material
Glass
Mica
Insulating Oil used in transformers
Paraffin Wax
India Rubber
Gutta Percha
Paper, as used for power cables
Paper, as used in telephone cables
Paper, paraffined, as used in condensers
Distilled Water
Pure Alcohol
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K
2—10
5—6
2—1
2.3
2.2—2.8
2.5—4
2.6—3.5
2—2.5
7.2
76
26
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