SEMICONDUCTOR

Question 1

Pure semiconductor

Answer 1

Germanium and silicon

Question 2

Impure semiconductor

Answer 2

P-type and N-type

Question 3

Doping

Answer 3

process of adding impurities to a semiconductor to increase its conductivity

Question 4

P-type Semiconductor

Answer 4

Obtained by adding small amount of tetravalent impurities. Effect of this is creation of holes and gaps in the semiconductors crystal, because the impurity attracts electrons and results in holes having positive charges. These holes can migrate throughout the crystal. The resultant semiconductor is called p type because the possibility of current is by the motion of positive charges.

Question 5

N-type Semiconductor

Answer 5

They are obtained by adding small amount of pentavalent element to the pure semiconductor In this type electrons are free to move in the crystal . Hence this is called N-type semiconductor due to presence of negative charged carriers in electrically neutral crystal

Question 6

Knee voltage

Answer 6

voltage at which the forward diode current increases rapidly

Question 7

Common base BJT

Answer 7

A type of BJT configuration where base terminal of transistor is a common terminal to both input and output signal

Question 8

Common emitter BJT

Answer 8

type of BJT confi. where input is taken from base terminal output is collected from collector terminal and emitter is common to both

Question 9

Common Collector BJT

Answer 9

A type of BJT confi where input is applied to base terminal and output signal is taken from emitter terminal. Collector terminal is common to both input and output signal

Question 10

Common base current amplification (α)

Answer 10

ratio of output current to input current

Question 11

Common emitter current amplification factor (β)

Answer 11

ratio of change in the collector current to the change in base current at a constant emitter voltage

Question 12

Relation btw alpha and beta

Question 13

Different modes of operation of BJT

Answer 13

on switch (J1 = J2 = F.B.)
off switch ( J1 = J2 = R.B.)
amplifier ( J1 = F.B. , J2 = R.B.)

Question 14

Reverse blocking mode

Question 15

Ideal Diode

Answer 15

in forward conduction region an ideal diode acts as a closed switch and in reverse blocking region it acts as an open switch

Question 16

Width of depletion layer

Answer 16

it increases with an increase in applied voltage

Question 17

Semiconductor diode is polarity sensitive

Answer 17

PN junction diode is a 2 terminal polarity sensitive device. The diode conducts when forward bias is applied and it will introduce zero resistance in the circuit. The diode does not conduct when reverse bias is applied and it will introduce infinite resistance in the circuit

Question 18

Doping in NPN and PNP transistor

Answer 18

Emitter is heavily doped
Base is lightly doped
collector is doped intermediately

Question 19

Working of NPN transistor

Question 20

Working of PNP transistor

Question 21

Transistor

Answer 21

A transistor is a three terminal device that can be used to conduct and insulate electric current or voltage

Question 22

Common collector circuit AKA

Answer 22

Grounded emitter circuit

Question 23

Diode is used in which circuit

Answer 23

rectifier

Question 24

depletion layer and R.B. , F.B.

Answer 24

F.B. reduced depletion layer while R.B. increases depletion layer

Question 25

Leakage in reverse blocking mode and temperature

Answer 25

leakage is constant at constant temperature

Question 26

what if reverse voltage is increased in diode beyond its inverse voltage

Answer 26

electrical breakdown takes place

Question 27

Inverse voltage

Answer 27

he maximum voltage that a diode can withstand in the reverse direction without breaking down or avalanching