Hi all I'm having problem solving the question below , anyone can guide me with the answer step by step .
Thank you all

 

It would be useful if we could see how far you can get.
For starters, can you tell us what Vzt, Izt, Izk, Zz, and Izm mean?

 

looks like piecewise linear model of a Zener diode:
http://www.ittc.ku.edu/~jstiles/312/handouts/Zener Diode Models.pdf

but...for par 'c': Can variable resistor RL go down to zero ohms?

 

Vzt = Zener test voltage , Izt = zener test current , Izt = zener knee current , Zz = Zener Resistance & Izm = Zener Maximum current.

Thanks sirs

 

Hi,

The first thing you would have to do is determine the model parameters of the zener.

Given that the test voltage is 4.8v at a test current of 36ma and internal resistance of 10 ohms that means that the zero current voltage is:
Vd0=4.8-0.036*10

So you have that voltage source in series with a 10 ohm resistor to start with, and that replaces the zener diode. This gives you a circuit with two voltage sources and three resistors which is solvable using standard methods.

See what you can do with this information.

 

any solution for this ?

 

Hello,

Do you know now to analyze a circuit with two sources and three resistors?

The zener gets replaced by a source with a series resistor. Then you solve the circuit.
For the Power question, you'll have to assume that the variable resistor never pulls the zener voltage lower than Vz0.
Vz0=Vd0=4.8-0.036*10=4.44

Can you figure out the rest?

 

any solution for this ?

You need to show YOUR attempt to answer YOUR homework problem. That will give us a starting point to see where you are going wrong and how we might best help you get back on track.

 

It might help if you sketch the typical Zener characteristic and then the piecewise linear model implied by the given parameters.