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Homework Help: Basic npn bjt problem

  1. Nov 13, 2017 #1
    1. The problem statement, all variables and given/known data
    bjt q5.png

    2. Relevant equations
    KVL

    3. The attempt at a solution
    Using KVL around BE loop
    0-0.6-i_e*(30*10^3)-15=0
    i_e=-0.52mA
    However, I stuck when I tried to find i_c and use KVL around CE loop/ CB loop
    For CE loop:
    10-i_c*(15*10^3)-Vce-i_e*(30*10^3)-15=0
    For CB loop:
    10-i_c*(15*10^3)-Vcb=0
    I got confused about how to relate Vce and Vcb. (here I guess it must be some kind of relationship that looks like Vbc-Vac=Vba)
    Also, it seems like it is operating in cutoff mode (both Vc and Ve>Vb), however, there is current flowing around the loop. So what is the mode that the transistor is actually operating in?
    Thank you!:confused:
     
  2. jcsd
  3. Nov 13, 2017 #2

    CWatters

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Circuit looks odd to me. Like common base configuration but the polarity of the emitter bias voltage is wrong ( should be -15v). Think the transistor is either off or they made a mistake?

    Otherwise I would suggest you assume Ic=Ie.
     
  4. Nov 13, 2017 #3

    NascentOxygen

    User Avatar

    Staff: Mentor

    Yes, try reversing the polarity of the 15v supply.
     
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