Another problem, voltage characteristic in a diode circuit

[amitjakob]

Good morning lovely people !

As I got some really helpful advice here yesterday i though i'd try it again, hopefully you haven't yet had too much from me (-:

So my question is concerning the attached PDF file (Last problem #3)

i am asked to find the current I_B in 3a) and 3c) but to my very low understanding wouldn't it simply be Vi/Ri (Ohms Law) ??

Thanks for the patience

 

[edmondng]

try kvl. looks like its a bjt (just zoomed in). factor in diode drop, Vi, etc etc

 

[amitjakob]

Thanx but ...

do you mind explaining a little bit more, I'm kinda newbie (-:
whats a bjt ?
thanks for the patience

 

[amitjakob]

try kvl. looks like its a bjt (just zoomed in). factor in diode drop, Vi, etc etc

Tried KVL on the most left handside mesh.
Im not sure its right though ...

i guessed V_Ri + V_B = V_i then substitute V_B=0.65V (pretty sure its a bad guess) and V_i=1V (Which is given)

Yeilds I_Ri=I_B= 93.75 microA ? makes sense ?