basic electronics btech morning

7/21/2019 Basic Electronics BTech Morning

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1. Which of the following element has four valence electrons?

(a) Silicon (b) Germanium

(c) Both (a) and (b) above (d) None of the above

2. ree electrons e!ist in(a) irst band (b) Second band

(c) "hird band (d) #onduction band

$. % collector collects

(a) electrons from the base in case of &N& transistor

(b) electrons from the emitter in case &N& transistor

(c) holes from the base in case of N&N transistor

(d) holes from the base in case of &N& transistor

'. % &N& transistor is made of

(a) Silicon (b) Germanium

(c) ither silicon or germanium (d) None of the above

. % transistor which of the following region is ver* lightl* do+ed and is ver*

thin?

(a) mitter (b) Base

(c) #ollector (d) None of the above

,. -n a &N& transistor with forward bias the emitter /unction

(a) is alwa*s reverse biased (b) o0ers ver* high resistance

(c) o0ers a low resistance (d) remains o+en

. -n a N&N transistor when emitter /unction is forward biased and collector

/unction is reverse biased the transistor will o+erate in

(a) active region (b) saturation region

(c) cut o0 region (d) inverted region

. -n a &N& transistor electrons 3ow(a) into the transistor at the collector onl*

(b) into the transistor at the base and the collector leads

(c) out of the transistor at base and collector leads

(d) out of the transistor at base collector as well as emitter leads



4. %rrow head on a transistor s*mbol indicates

(a) 5irection of electron current in emitter

(b) direction of hole current in emitter

(c) di0erent current in emitter

(d) drift current in emitter

16. Which of the following is not +rovided in a &N& transistor?

(a) Base (b) #ollector

(c) mitter (d) 5rain

11. Which of the following is the fastest switching device?

(a) 7" (b) B7"

(c) 89S" (d) "riode

12. " has

a) high in+ut im+edance b ) low in+ut im+edance

c) high out+ut im+edance d) both a and c

1$. % B7" is a:

a) current controlled current device b)voltage controlled current

device

c) voltage controlled voltage device d)either a or b

1'.7" is a

a) voltage controlled voltage device b)voltage controlled currentdevice

c) current controlled voltage device d)either a or b

1. 5rift current in the semiconductors de+ends u+on

a) onl* the electric ;eld (b) onl* the carrier concentration gradient

c) both the electric ;eld and the carrier concentration

d) both the electric ;eld and the carrier concentration gradient

1,. % <ener diode when used in voltage stabili=ation circuits is biased in

(a) reverse bias region below the brea>down voltage

(b) reverse brea>down region (c) forward bias region

(d) forward bias constant current mode

1. % semi conductor material without an* im+urit* is >nown as .



a) -ntrinsic semi conductor (b) !trinsic semi conductor (c) #onduction

semi conductor.

1. "he voltage gain in the common base con;guration is

.a) @igh (b)Anit (c) ess than unit*

1. 9nce a <ener diode goes into brea>down its does not

change much.a) Coltage (b) #urrent (c)5*namic im+edance.

14. When de+letion la*er increased it becomes .a) Deverse biasing (b)orward biasing (c)Demain constant.

26. 5iode can be used as a) %m+li;er (b)Decti;er (c)9scillator

21. <ener 5iode can be used as b) %m+li;er (b)Decti;er (c)Degulator

2$. -n +ure silicon:

a) the holes are the ma/orit* carriersb) the electrons are the ma/orit* carriers

c) the holes and electrons e!ist in eEual numbers

d) conduction is due to there being more electrons than holes

2'. &entavalent im+urities:

a) have three valence electrons

b) introduce holes when added to a semiconductor material

c) are introduced b* adding aluminum atoms to a semiconductor material

d) increase the conduction of a semiconductor material

2. When a silicon +Fn /unction diode is reverse biased:

a) a constant current 3ows over a large range of voltages



b) current 3ow is due to electrons in the nFt*+e material

c) current t*+e is due to minorit* carriers

d) the magnitude of the reverse current flow is usuall* less than 1 %

2,. "he base region of a +FnF+ transistor is

a) ver* thin and heavil* do+ed with holes

b) ver* thin and heavil* do+ed with electrons

c) ver* thin and lightl* do+ed with holes

d) ver* thin and lightl* do+ed with electrons

Section B

"rue and alse:

1. #ommon Base #on;guration F has Coltage Gain but no #urrent Gain.

2. #ommon mitter #on;guration F has both #urrent and Coltage Gain

$. #ommon #ollector #on;guration F has #urrent Gain but no Coltage Gain.

"he brea>down mechanism in a lightl* do+ed +Fn /unction under reversebiased condition is called (%) avalanche brea>down. (B) =ener brea>down. (#)brea>down b* tunnelling. (5) high voltage brea>down. %ns: %H.2 -n a # I connected transistor am+li;er with voltage I gain %v theca+acitance #bc is am+li;ed b* a factor (%) % v (B) %v 1J (#) %v 1J (5) 2 % v%ns: BH.$ or a large values of KC5SK a " I behaves as (%) Coltage controlledresistor. (B) #urrent controlled current source. (#) Coltage controlled currentsource. (5) #urrent controlled resistor. %ns: #H.' Demoving b*+ass ca+acitor across the emitterFleg resistor in a #am+li;er causes (%) increase in current gain. (B) decrease in current gain. (#)increase in voltage gain. (5)decrease in voltage gain. %ns: 5H. or an o+Fam+ having di0erential gain %v and commonFmode gain %c the#8DD is given b* (%) %v J %c (B) c v % % (#) 1 % % c v J (5) v c % % %ns: B%6 B%S-# #"D9N-#S 2H., When a ste+Fin+ut is given to an o+Fam+ integrator the out+ut will be(%) a ram+. (B) a sinusoidal wave. (#) a rectangular wave. (5) a triangularwave with dc bias. %ns: %H. @*steresis is desirable in SchmittFtrigger because (%) energ* is to bestoredLdischarged in +arasitic ca+acitances. (B) e0ects of tem+erature wouldbe com+ensated. (#) devices in the circuit should be allowed time forsaturation and desaturation. (5) it would +revent noise from causing falsetriggering. %ns: #



H. -n a fullFwave recti;er without ;lter the ri++le factor is (%) 6.'2 (B) 1.21(#) 1.4 (5) 2.6 %ns: %H.4 % minterm of the BooleanFfunction f(! * !) is (%) !′ J * J = (B) ! * =′ (#)! = (5) (* J=) ! %ns: BH.16 "he minimum number of 3i+F3o+s reEuired to construct a modFcounter is (%) (B) , (#) (5) %ns: #H.11 S+ace charge region around a +Fn /unction (%) does not contain mobile

carriers (B) contains both free electrons and holes (#) contains one t*+e ofmobile carriers de+ending on the level of do+ing of the + or n regions (5)contains electrons onl* as free carriers %ns: %H.12 "he im+ortant characteristic of emitterFfollower is (%) high in+utim+edance and high out+ut im+edance (B) high in+ut im+edance and lowout+ut im+edance (#) low in+ut im+edance and low out+ut im+edance (5)low in+ut im+edance and high out+ut im+edance %6 B%S-# #"D9N-#S$ %ns: BH.1$ -n a 7" at +inchFo0 voltage a++lied on the gate (%) the drain currentbecomes almost =ero (B) the drain current begins to decrease (#) the draincurrent is almost at saturation value. (5) the drainFtoFsource voltage is close

to =ero volts. %ns: # H.1' When an am+li;er is +rovided with current series feedbac> its (%)in+ut im+edance increases and out+ut im+edance decreases (B) in+ut andout+ut im+edances both decrease (#) in+ut im+edance decreases and out+utim+edance increases (5) in+ut and out+ut im+edances both increase %ns: 5H.1 "he freEuenc* of oscillation of a tunnelFcollector oscillator having M$6@ and # M $66+f is nearb* (%)2, >@= (B) 1, >@= (#) 1., >@= (5) 2.,8@= %ns: BH.1 "he control terminal (+in) of timer -# is normall* connected toground through a ca+acitor (O 6.61). "his is to (%)+rotect the -# frominadvertent a++lication of high voltage (B) +revent false triggering b* noisecou+led onto the +in (#) convert the trigger in+ut to shar+ +ulse b*di0erentiation (5)su++ress an* negative triggering +ulse %ns: BH.1 "he value of ri++le factor of a halfFwave recti;er without ;lter isa++ro!imatel* (%) 1.2 (B) 6.2 (#) 2.2 (5) 2.6 %ns: %H.14 "he three variable Boolean e!+ression !* J !*= J ! * J ! * = %6B%S-# #"D9N-#S ' (%) * J != (B) ! J =* (#) * J != (5) * J =! %ns: # *(!J !) J !=(* J *) M * J !=H.26 "he fanFout of a 89SFlogic gate is higher than that of "" gatesbecause of its (%) low in+ut im+edance (B) high out+ut im+edance (#) lowout+ut im+edance (5) high in+ut im+edance %ns: 5H.21 -n an intrinsic semiconductor the ermiFlevel is (%) closer to thevalence band (B) midwa* between conduction and valence band (#) closer tothe conduction band (5) within the valence band %ns: #H.22 "he reverse I saturation current of a silicon diode (%) doubles for ever*16P# increase in tem+erature (B) does not change with tem+erature (#)halves for ever* 1P# decrease in tem+erature (5) increases b* 1. times forever* 2P# increment in tem+erature %ns: %



H.2$ "he common collector am+li;er is also >nown as (%) collector follower(B) Base follower (#) mitter follower (5) Source follower %ns: #H.2' -n classI% am+li;er the out+ut current 3ows for (%) a +art of the c*cleor the in+ut signal. (B) the full c*cle of the in+ut signal. (#) half the c*cle ofthe in+ut signal. (5) $L'th of the c*cle of the in+ut signal. %ns: BH.2 -n an am+li;er with negative feedbac> (%) onl* the gain of the am+li;eris a0ected (B) onl* the gain and bandwidth of the am+li;er are a0ected (#)

onl* the in+ut and out+ut im+edances are a0ected

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