enter image description here I wanted to know if Vb in the trasistor in the photo is equal to the formula in red circle: Vb=R2*Vcc/(R1+R2)

  • \$\begingroup\$ No, it cannot be. \$\endgroup\$ – jonk Feb 13 at 6:53
  • \$\begingroup\$ If you would remove the transistor, it could be. If, without the transistor, the voltage across R2 is less than the Vbe which the transistor needs to turn on (about 0.6 V) then it could be true as well. But the value of R2 is such that the transistor will turn on so the formula does not apply, it ignores the influence of the transistor. \$\endgroup\$ – Bimpelrekkie Feb 13 at 7:46
  • \$\begingroup\$ Hello to electronics.stackexchange. Is your question a homework? \$\endgroup\$ – smajli Feb 13 at 7:46
  • \$\begingroup\$ @Bimpelrekkie Even if the transistor is removed, doesn't \$R_E\$ need to show up in the equation for \$V_B\$, since we are looking for a voltage with respect to ground rather than the emitter? \$\endgroup\$ – Elliot Alderson Feb 13 at 13:17
  • \$\begingroup\$ @ElliotAlderson You're absolutely correct, I missed that \$R_E\$ wasn't there. So my comment is valid for the case that \$R_E\$ is added to the formula, so the denominator \$R_1 + R_2\$ will become \$R_1 + R_2 + R_E\$ \$\endgroup\$ – Bimpelrekkie Feb 13 at 13:24

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