View attachment 1747103240972.jpeg
Can some one check my solution?

 

Can you check this
View attachment 349086

Now you are hijacking your own topic by changing to a different question. Yes i checked it and your results are all wrong other than Id=2.5mA.

Btw i would fail anyone for not showing units throughout solving problem.this is of highest importance, way higher than getting correct numeric value.
And you are skipping important steps. Homework is about convincing others that your thinking and problem solving is sound, not that you magically got some numeric value as a result. You pulled Va out of thin air and of course it is wrong as is everything that follows. And tiu are using shortcuts to keep track of sign rather than showing in a convincing way how did this turn out to be what you think it is

 

Now you are hijacking your own topic by changing to a different question. Yes i checked it and your results are all wrong other than Id=2.5mA.

Btw i would fail anyone fir not showing units throughout solving problem.

yes , you mean that only Id1=Id2=2.5mA is correct? how about the equation for R?

 

yes , you mean that only Id1=Id2=2.5mA is correct? how about the equation for R?

As already stated, you pulled Va out of thin air. The equation is otherwise correct but you need to keep track of units and explain sign changes.

 

As already stated, you pulled Va out of thin air. The equation is otherwise correct but you need to keep track of units and explain sign changes.

As you can see, on top is +5V right? then Va is 5v.

 

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Can some one check my solution?View attachment 349099

It’s far easier than that.
if both diodes have the same voltage drop and their anodes are connected together, what can you say about their cathode voltages?
Knowing that, what is the voltage across the resistor?
Knowing the voltage across the resistor and the current through it gives the resistance value by Ohm’s law.

 

Your solution is wrong because, once again, you won't take a step back and learn the fundamentals.

What is your reasoning for claiming that Va is 5 V?

Whatever it is, it is faulty. But, if you can explain what that reasoning is, perhaps we can help you understand why it is faulty, so that you can stop making similar basic mistakes in the future.

 

It’s far easier than that.
if both diodes have the same voltage drop and their anodes are connected together, what can you say about their cathode voltages?
Knowing that, what is the voltage across the resistor?
Knowing the voltage across the resistor and the current through it gives the resistance value by Ohm’s law.

Dont know what you mean? Can you show clear steps one by one

 

Dont know what you mean? Can you show clear steps one by one

I can number the points and leave a blank line between each of them.

 

hi lin,
Consider that you have 2,5mA flowing through each diode.

On one diode cathode, you have -2v source, so your resistance value has to create a 2V cancellation at that 2.5mA current.

E

 

I can number the points and leave a blank line between each of them.

Okay, please

 

no it is not... there is a current source between +5V and Va. they are NOT at the same potential. if the Va was 5V, what would be voltage across left diode?

 

I can number the points and leave a blank line between each of them.

First.
You know that both diodes have the same forward volt drop, which is 0.7V.
You know that both anodes are connected together.
What do you know about their cathode voltages?

 

no it is not... there is a current source between +5V and Va. they are NOT at the same potential. if the Va was 5V, what would be voltage across left diode?

Yes, a current source between them. How to calculate Va ?

 

answer our questions

 

hi lin,
Consider this method.
E

 

answer our questions

What is your question?

 

Post #13. If you can answer that simple question, the problem becomes trivial.

 

What is your question?

mine is in post #12
Ian0 has one in #13
an answer was also shared before that but you did not pick up on it.

 

no it is not... there is a current source between +5V and Va. they are NOT at the same potential. if the Va was 5V, what would be voltage across left diode?

Still 0.7v diode lock voltage across it.