# 電子學題目：求解理想二極體

http://img261.imageshack.us/img261/2962/002xh9.jpg

Update:

http://img517.imageshack.us/img517/1030/13069774jl...

Update 2:

Rating

If D1 is on, the V's voltage is 0V and the current flowing through D2 is (15-0)/5=3A. the current flowing through 10 ohm is (0-(-15))/10=1.5A. The two currents are not equal so V=0(volt) is wrong becasue the current can not flow from D1's k terminal to A terminal.

Assume D1 is off and D2 is on, the V's voltage is 5V. D2 is an ideal diode and the voltage drop is 0V so the voltage at D1's K terminal is 5V and D1 is off. This is the same as our assumption.

So D1 is off and D2 is on and the V's voltage is 5V.

Ans: 5V

這兩題D1接法不一樣，首先談解答給的題目，他的D1陰極是接地，而且陽極是接在+15上方，所以他一定會是順偏，所以才導致V1＝0。

另外你自己算的那題D1的陽極反而是接地，而且D2一定是順偏，因為他接在+15上方，然後D2順偏後的陰極電壓也還是高過D1陽極，所以他不會導通，換局話說整個電路D2 ON、D1 OFF。

所以I＝30/15＝1mA，V＝15-5*2＝5V

2007-09-14 15:09:47 補充：

你畫的跟解答的電路圖示不一樣的喔，請在確認一次，解答的電路欲求的V是畫在D2陰極下面，而且D1陰極是接地。

而你畫的D2陽極是接在你欲求的V，而D1陽極反而是接地。

Source(s): 我是成大電機研究生, 自己
• ޳
Lv 5

以目視來看

V點電壓為 0

如有錯請告知謝謝~~

大家再一起研究看看

2007-09-13 00:06:26 補充：

就算是15V 也一樣壓

這種題目先判斷二極體的狀態

因為題目沒給切入電壓,故不考慮二極體的壓降

仔細看,一個二極體接至系統最高電壓,一個二極體接至系統最低電壓

所以想也不用想,兩顆二極體一定全通,然後你就把二極體拿掉

解電路學,答案就出來了, 0 V 因為拿掉二極體後,中間接地,那電壓當然是 0V囉