# Ideal diode question

Hi,

I am stuck trying to work out a problem involving two ideal diodes.

http://img200.imageshack.us/img200/668/idealdiodev.jpg [Broken]

I need to find V and I. Aswell as which diode is on and off.

I have tried to solve it by assuming d1 is on and hence V is 0 but i cant get the right answers no matter what formula I try.

Any help would be greatly appreciated.

thanks
-Steve

Last edited by a moderator:

Remove D2 from the circuit. Work out the voltages at the nodes where D2 was connected. Decide whether D2 would be forward or reverse biased. Proceed from there.

Redbelly98
Staff Emeritus
Homework Helper
Welcome to Physics Forums.

I have tried to solve it by assuming d1 is on and hence V is 0 ...

Um, no, you can't conclude V is 0 from assuming D1 acts as a short.

Using the D1-is-on assumption, try solving the problem for both D2-is-on and D2 is non-conducting. See which assumption gives a consistent solution:

If D2 is on, do you get a positive value for the current I? (I.e., the diode is forward-conducting)​
or
If D2 is non-conducting, do you get a higher voltage on the left side than the right? (I.e., it is reverse-biased)​