Figure given below shows the transfer characteristics of a base biased CE transistor. Which of the following statements are true?

(a) At Vi = 0.4 V, transistor is in active state
(b) At Vi = 1 V, it can be used as an amplifier
(c) At Vi = 0.5 V, it can be used as a switch turned off
(d) At Vi = 2.5 V, can be used as a switch turned on

1. (a, c)

2. (a, c, d)

3. (b, c)

4. (b, c, d)

(b, c, d) Hint: The working of the transistor depends on  Vi.
Step 1: Find the result in each case.
From the given transfer characteristics of a base biased common emitter transistor, we note that;
(i) When Vi = 0.4 V, ther is no collection current. The transistor circuit is in an active state and is used as an amplifier.
(ii) When Vi = 1 V (This is in between 0.6V to 2V). The transistor is in an active state and is used as an amplifier.
(iii) When Vi = 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 the transistor is in saturation state and can use as a switch turned on state.