question_answer 30)

  Figure 9(EP).7 shows that transfer character-istics of a base biased CE transistor. Which of the following statements are true? (a) At  =0.4 V, transistor is in active state (b)At  = IV, it can be used as an amplifier (c) At  = 0.5 V, it can be used as a switch turned off (d) At  = 2-5 V, can be used as a switch turned on  

Answer:

  (b,c,d) From the given transfer characteristics of a base biased common emitter transistor, we note that (i) When Vi = 0.4 V, there is no collector current. The transistor circuit is m cut off state. (ii) When Vi = 1 V (which is inbetween 0-6 V to 2 V), the transistor circuit is in active state and is used as an amplifier.                                                                                   (iii) When yi = 0.5 V, there is no collector current. The transistor is in cut off state. The transistor circuit can be used as a switch turned off.                                                                 (iv) When Vi = 2.5 V, the collector current becomes maximum and transistor is in saturation state and can be used as switch turned on state. Thus, options (b, c and d) are true.