What is the Maximum Power Dissipation for a Zener Diode Regulator?

[roam]

Homework Statement

The following is a diagram of dc power supply with a Zener diode regulator. For what load current is the power dissipation of the Zener diode maximum? How would you find the approximate value of this maximum power dissipation?

[PLAIN]http://img40.imageshack.us/img40/7325/diagrami.png

The Attempt at a Solution

I think P_{z,max}=I_{z,max} V_z. Then to find V_z

V_z = I_z \times 100 \Omega

Is this right? I just know that I=I_z+I_L, but how do we work out
when is I_z maximum?

(I_L is the current through the load)

 

[vk6kro]

Assume an input of 12 V across the capacitor Cs.

What is the voltage across the 100 ohm resistor with and without a load?

So, what is the current in the 100 ohm resistor?

Where does this current go when there is a load and when there isn't a load?