21. In a NPN transistor if the emitter junction is reverse biased and collector junction is also reversed biased the transistor will operate in
a. active region
b. saturation region
c. cutt-off region
d. inverted region
22. In a normally biased NPN transistor the main current crossing the collector junction is
a. a drift current
b. a hole current
c. a diffusion current
d. same as the base current
23. A transistor has
a. Collector
b. Emitter
c. Base
d. II and III only
24. A diac is a semi conductor device which acts as a
a. 2 terminal unidirectional switch
b. 2 terminal bidirectional switch
c. 3 terminal bidirectional switch
d. 4 terminal multi-directional switch
25. In a NPN transistor , when emitter junction is forward biased and collector junction is reverse biased the transistor will operate in
a. active region
b. saturation region
c. cutt-off region
d. inverted region
26. Which of the following is necessary for transistor action ?
a. The base region must be very wide
b. The base region must be very narrow
c. The base region must be made of some insulating material
d. The collector region must be heavily doped
27. A triac is a semi-conductor device which acts as a
a. 2 terminal unidirectional switch
b. 2 terminal bidirectional switch
c. 3 terminal bidirectional switch
d. 4 terminal multi-directional switch
28. The common base short circuit current gain alpha for the transistor is
a. 0.99
b. 1.01
c. 1.001
d. 0.990
29. The common -emitter short circuit current gain
a. 1
b. 199
c. 99
d. 9.9
30. In a transistor leakage current mainly depends on
a. doping of base
b. size of emitter
c. rating of transistor
d. temperature
