Topic: Analog Circuits
Common emitter DC current gain of the transistor is 100. The current through the 10 V Zener diode (assuming V_BE of the transistor is 0.7 V) is:
- A. 10.3 mA
- B. 19.3 mA
- C. 20 mA
- D. 40 mA
Answer: A. 10.3 mA
Explanation: With β = 100 and V_BE = 0.7 V, applying KVL in loop 1 gives -10 + V_BE + I_E R_E = 0, so I_E = (10 - 0.7) / 10 = 0.93 A = 930 mA. Base current I_B = I_E / (1 + β) = 930 / 100 = 9.3 mA. Total current from supply I_1 = (20 - 10) / 0.5 kΩ = 20 mA. Therefore, Zener diode current I_Z = I_1 - I_B = 20 - 9.3 = 10.7 mA (closest given option is 10.3 mA).