試題詳解

17. Electromagnetic standing waves are set up in a conducting cavity resonator in the form of a hollow metal box. The waves bounce back and forth between two parallel surfaces separated by 0.8 cm. What is the minimum resonant frequency for such a resonator?
(A) 3.30 GHz
(B) 4.42 GHz
(C) 12.4 GHz
(D) 15.5 GHz
(E) 18.8 GHz