Solve Ideal Diode Problem: V & I Calculation

[steveH]

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 can't get the right answers no matter what formula I try.

Any help would be greatly appreciated.

thanks
-Steve

 

[overt26]

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]

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)​