A cable consisting of a wire 3 mm in diameter and insulated with 3 mm thick dielectric of relative permittivity 4.5 is placed in water. Calculate the capacitance of 1 km length of the cable.

A cable consisting of a wire 3 mm thick dielectric of relative permitively 10. Calculate the capacitance of 1 km length of the cable.

1 cm^(3) of gold is drawn into a wire 0.1 mm in diameter. Find the length of the wire.

A capacitor is composed of two plates separated by a sheet of insulating material 13 mm thick and or relative permittivity 4. The distance between the plates is increased to allow the insertion of second sheet 5 mm thick and of relative permittivity in_(r) . If the capacitance of the capacitor so formed is 1/3 of the original capacitance , find in_(r) .

A parallel plate capacitor has two plates of dimensions 10 cm xx 7 cm separated by a distance of 0.7 mm. A glass plate of thickness 0.4 mm (dielectric constant = 6) and another dielectric medium of thickness 0.3 mm (dielectric constant = 2.5) are placed between the plates of the capacitor. Calculate the capacitance of the capacitor before and after introduction of the dielectric media.

The cross section of a cable is shown in fig. The inner conductor has a radius of 10 mm and the dielectric has a thickness of 5 mm . The cable is 8 km . Long. Then the capacitance of the cable is [log_(e) 1.5 =0.4] . .

The inner and outer radii of a coaxial cable are 0.1 mm and 0.6 mm respectivley.If the core material has dielectric constant 12, calculate the capacitance per metre of the cable.

A lead pencil consists of cylinder of wood with a solid cylinder of graphite fitted into it. The diameter of the pencil is 7 mm. the diameter of the graphite is 1 mm and the length of the pencil is 10 cm. Calculate the weight of the whole pencil in grams correct to three places of decimals if the specific gravity of the the wood is 0.6 and of the graphite 2.3.