阿摩線上測驗
23. A microwave oven operates with sinusoidal microwaves at a frequency of 2400 MHz. The height of the oven cavity is 25 cm and the base measures 30 cm by 30 cm. Assume that microwave energy is generated uniformly on the upper surface of the cavity and propagates directly downward toward the base. The base is lined with a material that completely absorbs microwave energy. The total microwave energy content of the cavity is 0.50 μJ. What is the amplitude of the electric field? (c = 3.00 x 108m/s, μ0 = 4πx 10-7 T m/A, ε0 = 8.85 x 10-12 C2/N m2)
(A) 2500 V/m,
(B) 1900 V/m,
(C) 2200 V/m,
(D) 2800 V/m,
(E) 1600 V/m.
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統計： 尚無統計資料
統計： 尚無統計資料
詳解 (共 2 筆)
助人為本
#7410365
所以解這題題目有給總電磁波總能量和空間體積
要想到能量密度的公式
然後能量密度又可以寫成1/2u0E0^2
所以兩個式子整理在一起
可以整理出這個式子
所以這題頻率、c、u0都是障眼法
沒有用到
所以套完公式可以得到2200
ㅤㅤ
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