determine the voltage at each point

[paulmdrdo]

determine the voltage with respect to ground at each point. assume practical model.

where would I start here?

 

[betwixt]

Some subtle clues in there already - like A and D are directly across the voltage sources.
As 25V is higher than 8V, the diodes are conducting so simply deduct Vf (forward voltage of the diodes) from 25V to get the voltage at point B and add it to the 8V to get the voltage at point C. If you need to take into account the current actually flowing it is the difference between battery voltages (25-8) = 17V less Vf of both diodes then divided by R.

Brian.

 

[paulmdrdo]

do you mean like this,

25-0.7-0.7 = 23.6v at point B

23.6+8 = 31.6v at point C

but the answer in my book says that at point B the voltage is 24.3v and at point c the voltage is 8.7v? why is that?

 

[betwixt]

simply deduct Vf (forward voltage of the diodes) from 25V to get the voltage at point B and add it to the 8V to get the voltage at point C

25V - Vf = 24.3V
8V + Vf = 8.7V

That is using 0.7V as Vf of course. You added 'B' to Vf instead of 8V.

Brian.

 

[paulmdrdo]

can we use kvl here?

 

[betwixt]

I'm not sure what you mean by 'kvl' but if its Kirchoff's Laws, yes you can but why, this is a simple series circuit with current flowing along only one path.

Brian.