Transistor as SwitchEasyQuestion 20236
Question
A BJT acts as a closed switch (saturated) when:
- ABase current is zero
- BBoth junctions are forward biased and V_CE is minimum (~0.1–0.2 V)Correct
- CBase-emitter junction is reverse biased
- DCollector current is zero
Correct answer
Both junctions are forward biased and V_CE is minimum (~0.1–0.2 V)
Explanation
Saturation: both EB and CB junctions are forward biased → maximum collector current for given V_CC → V_CE,sat ≈ 0.1–0.2 V → transistor acts as closed switch. Cutoff: I_B = 0, both junctions reverse biased → I_C ≈ 0 → open switch.