# Zener diodes

1. Aug 5, 2014

### ranju

In the given circuit we have to find the output voltage , the voltage drop across resistance RL (RL = 10KΩ) and the current through the zener diode having zener voltage VZ = 50V

By this question I want to be clear about the way to solve circuits with zener diode...please explain the reasoning.. I have studied that in forward bias , zener diode is shorted..in reverse it is open.. but how to apply it... please explain somewahat in this problem..!!

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2. Aug 5, 2014

### Staff: Mentor

No, in reverse bias a Zener diode is not open. Can you show us the V-I characteristic curve of a typical Zener diode? When you read about Zener diodes on wikipedia.org, what does it say? How does avalanche breakdown come into play?

3. Aug 5, 2014

### ranju

See first of all I would like you to give me the way how you would solve the circuit I gave...so that I can be somewhat clear...

4. Aug 5, 2014

### Staff: Mentor

No, that's not how the PF works. We require that you show some effort of your own, before we can provide tutorial help. Especially since the wikipedia entry is fairly clear and instructive.

Please read that article, and see if you can answer your question yourself. Post your work on the solution, and ask specific questions if you still have them.

5. Aug 5, 2014

### ranju

bur what I want to be clear about is not there in wikipedia..I am familiar with that theory but not getting how to apply...!! here the diode is in reverse bias..but how to move on further....
I am actually not getting this thing.. I really need your help..

6. Aug 5, 2014

### Staff: Mentor

What are you not understanding about the V-I characteristic of a Zener diode? What do those curves look like? How can you use that curve to determine the voltages and currents in the circuit that you drew?

7. Aug 6, 2014

### CWatters

What berkman said.

You need to look at and understand the I-V characteristics of a Zener diode.

When you first learn about diodes you are usually taught that a forward biased diode is like a short circuit and a reverse biased diode is like an open circuit. However that is a very simplistic model. You now need to learn about more accurate models.

For example what happens if you apply a large reverse bias voltage? Does a reverse biased diode always behave like an open circuit?