11. What is the reactance of a 7-pF capacitor at 2 GHz? 12. What value of capacitance is required to produce 50ohm of reactance at 450 MHz?

1.3 A coaxial cylindrical capacitor is to be designed with an effective length of 10 cm. The capacitor is expected to have a capacitance of 100 pF and to operate at 11 kV, 1000 kHz. Determine the required thickness if the required insulating material is Polytetrafluoroethylene (P.T.F.E.), &r= 2.0, Eb = 250 kV/cm. Allow a factor of safety of 4 and take to = 8.85x10-1² F/m.

A ceramic capacitor has a value of C=10,000 pF. The capacitor consists of a dielectric disc between two paralell metal disc plates. The dielectric disc has a relative permittivity of 40 and a conductivity of 10-12 S/m. The diameter of the disc plates is 1 cm. The voltage across the plates is 100 V. Find the leakage current density in the dielectric in mA/m2. Round off your answer to one decimal.

2.6