[SOLVED] Voltage: Ref. to ground with switch at position

[unlucky]

Can someone tell me if if my answers are correct (or wrong)? I will explain how I arrived at my conclusions if one of my answers is wrong (not that it would mean anything).

Voltage: Ref. to ground with switch at position
Are these right? I came up with:
A.__5V____
B.__0V____
C.__5V____

 

[davoud]

Okay. all answers are true but for ideal diode. if diodes are not ideal you should calculate diode effect at B & C (especially B situation) .

 

[kalbun]

Almost correct. A real diode has a voltage drop across its pin. So, in condition B you will read this drop (value varies with model, typically is something around 0.5V)

 

[unlucky]

I did a search to see the symbol of a real diode vs. an ideal diode. I'm very disappointed to see that the diode in my original post could be either. Nevertheless I'm glad you pointed this out and for argument's sake I'm going to assume it's an ideal. It would simply give me a headache if it were otherwise.

But amidst my confusion and being unsure, I looked at the drawing again. I know I may sound a little nutty and am probably overlooking something very elementary and not seeing something I should already know, but I ask, "When the the switch is in position B, can we be absolutely certain that there can be no voltage/current whatsoever flowing from Ref. to ground?"

 

[davoud]

Is Ref just a point for measuring or connection to a circuit ?
If Ref is a point for measuring and if we assume diode is ideal thus we will be certain that voltage of this point is zero at B. however current of R1 is 1ma and current of R2 is zero.

 

[andre_luis]

...I'm going to assume it's an ideal..."When the the switch is in position B, can we be absolutely certain that there can be no voltage/current whatsoever flowing from Ref. to ground?"

Assuming its diode model is really an ideal one, all current crossing Vref flows through diode net, due it is short-circuited to ground.
Thus, no more voltage remains at Vref ponit in order to generate some voltage drop.

+++

 

[unlucky]

Is Ref just a point for measuring or connection to a circuit ?

I would think it would be both.

If Ref is a point for measuring and if we assume diode is ideal thus we will be certain that voltage of this point is zero at B. however current of R1 is 1ma and current of R2 is zero.

And I do get the same with current at R1. I'm glad you confirmed that too because I did it earlier in the day and came up with the same.

- - - Updated - - -

That clears my mind more.