Zener diode exercise solved by me,is it correct?

[Questions999]

Homework Statement

We have Vz=6.8 V and Iz=5 mA,rz=20 Ohm,Izk=0.2 mA, R=200 Ohm and the source V= 9 volt
a)Find the output voltage when we have the input voltage with the nominal value of 9 Volt.
b)Find for the nominal value of the voltage,which is the maximum load current for which the diode works in the breakdown region?
c)Find the smallest value of the voltage source for which the diode still works in the breakdown region,while in the charge flows 1/2 of the maximum load current. How do I do this?

Homework Equations

I have included them in the solution

The Attempt at a Solution

Solution for the first one a)http://i.imgur.com/Jgn1bWN.jpg
b)http://i.imgur.com/wJYLCAG.jpg
c) I don't know how to do this
Are my solutions correct? Can you give me a clue on how to do c?

 

[gneill]

Hi Elaia06,

Can you post a circuit diagram? The implied circuit configuration should be obvious, but it's good to be certain.

Your first image is supposedly a solution for part (a) but it doesn't seem to address the question. Instead it appears to be dealing with output voltage variation and introducing some values not specified in the problem statement. For your part (b) image you have assumed a minimum source voltage of 8 V. Why, when the problem statement says that the nominal value of 9 V should be used?

As a suggestion, the equations that you're posting as images would not be difficult to type into the text of your post. Using the Advanced editing pane you have the access to the appropriate symbols, and you can also use LaTex syntax if you need to portray fancier equations.