Transistors

Question 1

The various junctions in a transistor

Answer 1

1] Emitter
2]Base
3]Collector

Question 2

Emitter junction

Answer 2

Is highly doped and medium sized junction

Question 3

Base junction

Answer 3

Is lightly doped and very thin in size

Question 4

Collector junction

Answer 4

Is moderately doped and large in size

Question 5

r(input)

Answer 5

[/\V(BE)]/[/\I(B)]

Where :
/\ —> delta

Question 6

A.C current gain( beta)

For common emitter configuration

Answer 6

Beta = |/\Ic| / |/\Ib|

Where /--> delta

Question 7

Range of beta(A.C. Current gain) for common emitter configuration

Answer 7

20

Question 8

AC current gain for common base configuration (alpha)

Answer 8

Alpha= |/\Ic| / |/\Ie|

Question 9

Range of ac current gain for common Base configuration

Answer 9

0.95

Question 10

Relationship between alpha and beta

Answer 10

Alpha = beta/(1+beta)

Beta= alpha/ (1-alpha)

Question 11

Common emitter amplifier
1]current gain =
2]voltage gain =
3]power gain =

Answer 11

1] beta = |/\Ic| / |/\Ie|
2]Av = /\Vc / /\Vb = beta x (Rout/Rin)
3] Pout/Pin = beta^2 x (Rout/Rin)

Question 12

Beta is always

Answer 12

Greater than 1

Question 13

Oscillator always uses

Answer 13

Positive feedback

Question 14

Condition to work as an oscillator

Answer 14

|A x beta| = 1

where beta is the feedback factor

Question 15

Frequency determination of an oscillator

Answer 15

1/2||(LC)^1/2

Question 16

For a transistor switch the active stage is achieved

Answer 16

At an intermediate input voltage

Question 17

In transistor switch Value of output voltage

Answer 17

Decreases linearly till its value is less than 1V

Question 18

In cut off region of transistor switch

Answer 18

Vi

Question 19

Graph for transistor switch

Answer 19

______