insulation resistance

-metre Copper Metal 1.7x10 - 8 Iron Metal 9.68x10 - 8 Manganin Alloy 48x10 - 8 Nichrome Alloy 100x10 - 8 Pure Silicon Semiconductor 2.5x 10 3 Pure Germanium Semiconductor 0.6 Glass Insulator 10 10 to 10 14 Mica Insulator 10 11 to 10 15 The reciprocal of resistance of a..

Substances which do not allow electricity to pass through them easily are called insulators. These are made from materials which have a high resistance. Some substances which are insulators are air, plastic, cotton, rubber, wood, paper, glass, pure water, etc. Substanc..

Substances which allow electricity to pass through them easily are called conductors. These are made from materials which have low resistances. Metals like copper, aluminium, silver, iron, brass and also salt solutions are good conductors of electricity. Substances which do not allow ele..

In metals, the conduction band and valence band partly overlap each other and there is no forbidden energy gap. In insulators, the conduction band is empty and valence band is completely filled and forbidden gap is quite large = 6 eV. No electron from valence band can cross over to c..

) 44 x 10 -6 Nichrome (alloy of Ni, Cr, Mn and Fe) 100 x 10 -6 Insulators Glass 10 10 - 10 14 Hard rubber 10 13 - 10 16 Ebonite 10 15 - 10 17 Diamond 10 12 - 10 13 Paper (dry) 10 12 Note Good conductors possess low resistivity..

The important uses of silicones are: 1) These are used in making electrical insulations. 2) These are used in making heat resistant container..

The heating effect of current is utilized in electrical heating appliances such as electric iron, room heaters, water heaters, etc. All these heating appliances contain coils of high resistance wire made of nichrome alloy. When these appliances are connected to power supply by insula..

Another device that harnesses solar energy is the solar cell. Solar cells are expensive and are used only when supplying electricity becomes difficult. Solar cells are the devices where solar energy is directly converted into electricity. Sunlight can be used to run machinery and generate elec..

It consists of a soft iron core made of laminated sheets well insulated from each other. The coils P 1 P 2 and S 1 S 2 are wounded on the same core. The coil P 1 P 2 is a primary coil connected to AC source and S 1 S 2 is a secondary coil connected across a load resistan..

The hydrolysis of monotrichloro silanes RSiCl 3 gives cross-linked polymers. By regulating the conditions, the condensation can be stopped at any stage and the chains or rings of desired lengths can be obtaine..