Answer Happy

1. A capacitor has two parallel metal plates measuring 0.45 m square each. The distance between the plates is 1 cm in free air. If a dielectric material whose permittivity is 4 and 5 mm thick is placed in the upper plate, leaving an air gap between the bottom plate and the dielectric, what is the capacitance of the capacitor? 2. A coaxial cable has a 10 mm diameter inside conductor and a metallic sheath with an inside diameter of 20 mm. If the insulating medium has a dielectric constant, k = 2, and a permittivity of 1.113 x 10 10, what is the capacitance between the conductor and the shield per km? 3. A lead-sheath cable for underground service has a copper conductor (diameter = 0.350 inch) surrounded by 0.20 inch wall of rubber insulation. Assuming the dielectric constant of 4.3 for rubber, calculate the capacitance of the cable per mile length. 4. A capacitor is composed of two plates separated by a 3 mm insulation whose dielectric constant is 4. An additional piece of 6 mm insulation is inserted between the plates. What is the dielectric constant of the additional insulation if the capacitance of the capacitor decreases to half as much of its original value?