Analyzing circuit with Silicon and Zener diode

[JasonHathaway]

Homework Statement

Determine Vout, the current flowing through R and power power dissipated the Zener diode.

Homework Equations

Circuit analyzing techniques.

The Attempt at a Solution

I've done this problem by assuming each diode is off while ignoring the other.

E.g. Applying KVL: -24+VD=0 --> VD=24 (Silicon diode is on and will be replaced with 0.7V voltage source).
Applying KVL again: -24-VDZ --> VDZ=-24 (Zener diode is reverse biased and will be replaced with VZT, which 12V voltage source).

Is this approach correct?

 

[NascentOxygen]

Can you explain why someone might construct this crcuit?

 

[CWatters]

That was a good hint from NascentOxygen.

Make sure you understand what Zener diodes are commonly used for.

 

[rude man]

I've done this problem by assuming each diode is off while ignoring the other.

Not a good idea. Why do you assume the diodes are off? They're not.

 

[NascentOxygen]

Not a good idea. Why do you assume the diodes are off? They're not.

Poster is closely following a generalized technique he has been taught. Assume one "state" and prove or disprove it is true. With experience, will be able to short-circuit his procedures.