TEST-3 (DIGITAL ELECTRONICS)-(EECTRONIC)

1. The difference between the number of atoms in a unit cell of a BCC crystal and  an FCC crystal is
a) 1                                               b) 2                                               c) 4                                          d) 6    
2. The temperature alone which an antiferromagnetic material because paramagnetic is called
a) Neel temperature               b) peak temperature            c) critical temperature               d) weiss temperature
3. The magnetization ‘M ‘ of a superconductor in a field of H is
a) extremely small                              b) –  H                                   c) -1                              d) zero     
4. An LED made using GaAs emits radiation in
a) Visible region                   b) ultraviolet region                c) Infrared region          d) Microwave frequency region
5. Which one of the following in a trivalent material ?
a) Antimony                        b) phosphorous               c) Arsenic                        d) Boron
6. The Ohms law for conduction in metals is
a)  J =  E                             b)  J = E/ σ                         c) J  σ  E                          d)  J    E /σ
7. Mobility is defined as   
a) diffusion velocity per unit field                                   b) drift velocity per unit field   
  c) displacement per unit field                               d) number of free electrons / number of bound electrons
8.  Atomic number of Silicon is
a) 12                                    b) 13                                       c) 14                                                  d) 15     
9. The Gunn diode is made of
a) Silicon                           b) germanium                      c) Gallium arsenide                      d) selenium   
10. The Laplace transform of sinwt is
a) s / (s2 +w2   )                  b) w2 / (s2 + w2 )                    c) s2 / (s2 + w2 )                                  d) w / (s2 + w2 )
11. What is the inverse laplace transform of e – as / s ?
a)  e – at                               b) u ( t-a)                               c) s ( t – a )                                      d)   ( t-a ) u ( t –a )
12. The total capacitance of two capacitors is 25 F  when connected in parallel and 4 F when connected in series . The individual capacitances of two capacitors   a  r e
a) 1 F and 24 F                      b) 3 F and 21 F                          c) 5 F and 20 F                         d) 10 F and 15 F

13.  Which of the following theorems can be  applied to any network- linear or non- linear, active or passive, time- variant or time invariant ?
a) Thevenin theorem     b) Norton theorem       c) Tellegen theorem      d) superposition theorem
14. A series RLC circuit has  w 0 =   10 5  ,  Q = 50 ,  R = 400 .The value of C is
a) 250 P F                                  b) 1000 P F                           c) 500 P F                                     d) 1.25  P F  
15. A two part network is reciprocal, if and only if
a) Z11 = Z 22                                  b) B C  – AD = -1                             c)  Y 12  = – Y 21                       d) h 12 = h 21
16. The average value of the full- wave rectified sine wane with period  , and a perk value of   v m is
a) 0.707 Vm                                     b) 0.5 V m                               c) 0.637 Vm                           d) 0.318 V m
17. In a half wave rectifier , if an  a.c. supply is 60 HZ , then  what is the a.c. ripple at output ?
a) 30 HZ                                         b) 60 HZ                                       c) 120 HZ                                     d) 15  HZ    
18. The ripple factor in case of a full – wave rectifier is
a)  1.21                                       b) 0.50                                       c) 0.48                                   d)  1.0
19. The maximum efficiency of half wave rectifier is
a) 33.33 %                                     b) 430.60 %                                 c) 50.00 %                               d) 68.00 %  
20. The output impedance of a BJT under common- collector configuration is
a) low                                        b) high                                      c) medium                                       d) very high
21. If ICEO = 410  A , ICBO = 5  A and I B = 30   A , the collector current  is
a) 415  A                                  b) 440   A                              c) 445  A                                            d) 2.84  A    
22.  A bipolar junction transistor with  forward  current transfer ratio X = 0.98 , when working in CE mode provides current transfer ratio   as
a) 98                                         b) 0.02                                             c) 49                               d) 0.49
23. Which of the following is a self complementing code ?
a) 8421 code                            b) excess – 3 code                            c) pure binary code                    d) gray code   
24. A number is expressed  in binary  two’s complement as 10011 its decimal equivalent value is
a)  19                                      b) 13                                         c) – 19                                      d) – 13
25. What is the Gray code word for the binary 101011 ?
a) 101011                                 b) 110101                                  c) 011111                           d) 111110
26. The hexadecimal representation of ( 657 ) 8  is

a) 1AF   H                                          b) D 78    H                                      c) D 71    H                                   d) 32 F     H
27. Consider the Boolean expression 
         X = ABCD   +  A B  C D  + A B C D + A B C D
  The simplified form of X is
a)  C + D                                  b)   B C                                   c) C D                                       d) B  C
28.What is the Boolean  expression  A  + B equal to

a) AB  + A B                              b ) A B  +  A B                         c) B                                      d) A 
29. What is the minimum number of NANO gates required to implement  A + A B +  A B C ?
a) 0                                    b) 1                                           c) 4                                       d) 7 .
30.If the output of a Logic gate  is ‘ 1 ‘ when all  its input ‘ O ‘ . Then the gate is either
a) ANAND    or an EX – OR gate            b) A NOR or an EX- NOR gate  
c) An  Or or an EX – NOR gate           d) An AND or an EX – OR gate
31. Which one of the following can be used as parallel to series convertor ?
a) Decoder                       b) digital counter                     c) multiplexer                  d) Demultiplexer
32. The number of 4- line – to – 16 line decoders required  to make an  8- line – to  256 line decoder is ?
a) 16                                      b) 17                                         c) 32                                d) 64   
33. What is the number of select lines required in a single input n – output demultiplexer ?
a) 2                                    b) n                                         c) 2 n                                       d) w g 2 n 
34. A T- flip flop function is obtained from  a J K  flip flop . The connection needed at the input  must be
a) J = K = 1                        b) J= K= O                   c) J = 1 and K = 0         d)  J = 0 and K = 1
35. The characteristic   equation of the T flip flop in given by
a) Q n + 1 = TQ n               b) Q n + 1 = TQ n + Q n T           c) Q n + 1 = T Q n           d) Q n + 1 = T Q n
36. Laser is based on the principal of
a)  Stimulated emission             b) Spontaneous emission           c) Radiation     d) Polarization
37. Which one of the following is a unidirectional and non- linear elements?
a) Capacitor                        b) Diode                            c) Resistor                     d) inductor
38. Super position theorem is applicable to the network containing

a) Unilateral elements      b) Non – linear elements      c) Linear elements        d) all 
39. Series RLC circuit is an example of
a) Band pass filter                    b) Band reject filter               c)  All pass filter      d) High pass filter 
40. 1 Nibble =  ……………………….. bits
a) 2                                        b) 4                                      c) 8                                           d) 1
41. Total number of NAND gates required to implement half adder is
a) 4                                       b) 5                                        c) 9                                            d) 6
42. The electron mobility of Ge is equal to
a) 3800 cm 2 /  v sec     b) 1300 cm 2 / v sec     c) 1800 cm 2 / v sec      d) 500 cm 2 / v sec
43. Energy gap at OK of Si is
a) 0.785  e v                          b) 1.21  e v                             c ) 0.72   e v                            d) 1.1 e v   
44. Which one of the following is fastest switch ?
a) Tunnel diode     b) photo diode     c) PIN diode     d) laser
45. ……………….. in a vottage contraected device
 a) B J T                                      b) F E T                                          c)   MOSFET                                d) All
46.  When both collector junction and Emitter junction are forword beased, what is the region of operation?
a) cut off                                       b) active                                          c) saturation                     d) reverse active 
47. The Stability s for base register biasing is
a)                                                   b)    + 1                                          c)    /    + 1                         d)    / 2
48. The laplace transform of a unit impulse is
a) 1                                                        b) 1/ s                                            c) 0                                                  d) 1/ s 2
49.  KCL is based on the
a) Law of  conservation of change       b) Law of conservation of energy     c) both a and b      d) none
50. RMS value is used for
a) D. C power calculation                       b)   A. C power calculation                  c) both                        d) none
51.  If (  11  X 1 Y  ) 8 = ( 12 C 9 ) 16 then the value of  x and y are
a) 3 and 1                                    b) 5 and 7                                 c) 7 and 5                                        d) 1 and 5
52. The BCD code for a decimal  number ( 874 )10  is

a)  ( 10000 111 0100) BCD                                            b) ( 010001111000 ) BCD   
 c) ( 100001000111) BCD                                              d) ( 011110000100) BCD
53. The range of intigers that can be represented by an n – bit 2 ‘ s  complement number system is
a)  – 2 n-1 to ( 2 n-1 -1 )                                                               b) – ( 2 n-1 -1 ) to ( 2 n-1 -1 )    
 c)  – ( 2 n-1 + 1 ) to 2 n -1                                                          d) – ( 2 n-1 + 1 ) to ( 2 n -1 – 1)
54. The maximum depletion layer width in silicon is
a) 0.143  m                                b) 0.57                                c)    1    m                            d) 1.143 
55. Thermal runaway will take place if the quiescent point is such that
a) V CE  >1/ 2 VCC                       b) V CE   <  VCC                            c) V CE < 2  V CC                      d) V CE   < 1/ 2   VCC
56. The unit of a thermal resistance of a semiconductor device is 
a) Ohms                                            b) ohms / 0 C                              c) 0 C / o h ms                               d) 0 C  / watt
57. Light travels along the optical fibles by which mechanism?
a)  Refraction                                  b) reflection                               c) scattering         d) total  internal reflection
58. The frequency range of very high frequency is
a)  300 MHZ  – 3000 MHZ          b) 30 MHZ  – 300 MHZ           c)   3 MHZ – 30 MHZ      d)  300 HZ – 3000 HZ
59. The internal resistance of a current source  used in the model of a BJT while amalyzing a circuit using BJT is
a) very low                                       b) very high                                  c) zero                                   d) infinity
60.  The transistor is said to be useful to be configured as an amplifier when its  is
a) less than 0                                  b) between 0 and 1               c) between 1 and 50               d) > 50

Electronic answer key- (I)

 

1.  B                 2. A                                             3. B                              4. C
5. D                  6.  A                                            7.  B                             8. C
9. C                 10. D                                            11. B                           12. C
13. C                14. C                                           15. B                            16. C                     
17. B               18. C                                            19. B                            20. A
21. D               22. C                                             23. B                          24. C      
25. D               26. A                                            27. C                           28. B
29. A                30. B                                           31. C                           32. B
33. D               34. A                                           35. B                          36. A
37. B                38.  C                                           39. A                          40. B
41. B                42. A                                           43. B                           44. A
45. B                46. C                                           47. B                            48. A
49. A                50. B                                           51. A                            52. A
53. A               54. D                                           55. A                             56. D
57. D               58. B                                            59. B                             60. D

TEST-3 (DIGITAL ELECTRONICS)-(EECTRONIC)

Q.1 The flip-flip circuit is…….

a) Unstable                  b) multistable
c) Monostable             d) bitable

Q.2 A digital counter consists of a group of

a) Flip-flop
b) half adders
c) Full adders
d) None of the above

Q.3 RAM memory represents …………..memory.

a) Record- attenuated
b) Read- audio
c) Radio-amplifies
d) Random-access

Q.4 ROM memory represents …………….memory

a) Read-out                 b) Record- oscillation
c) Register open           d) Read- octave

Q.5 A temporary memory is destroyed ………….

a) When power is switched off
b) In few milliseconds
c) In few seconds
d) In few minutes

Q.6 ………… is a permanent memory.

a) ROM only
b) RAM only
c) Both ‘a’ and ‘b’
d) Either ‘a’ and ‘b’

Q.7 ………….is a volatile memory.

a) ROM
b) RAM
c) Either ‘a’ and ‘b’
d) Both ‘a’ and ‘b’

Q.8 LCD display represents

a) Light decoding device
b) Liquid crystal display
c) Lead cascade demonstrator
d) Linear digital demonstrator

Q.9 LED display represents.

a) Loop emitter decoder
b) Long emission die
c) Light emitting diode
d) Logic electrostatic diode

Q.10 For LCD display which of the following liquid crystals is used?

a) Aqua regia              b) Nemanic fluid
c Liquid boron             d) Mercury

Q.11 ………… needs D.C. forward voltage to emit light.

a) LCD                         b) LED
c ) both a and b            d) None of the above

Q.12 A digital voltmeter has…………. Input and ……. Output

a) Digital, digital         b) digital, analog
c) Analog, analog        d) analog, digital

Q.13 …….. Display consumer least amount of power.

a) LED
b) LCD
c) Fluorescent display
d) All displays consumes same power

Q.14 Which of the following memories has both read and write capabilities?

a) ROM only
b) RAM only
c) Both ‘a’ and ‘b’
d) None of the above

Q.15 A 4-bit counter with four flip-flops will cont up to decimal.

a) 8                             b) 15
c) 31                            d) 63

Q.16 PROM stands for.

a) Positive read only memory
b) Permanent read only memory
c) Polarized read only memory
d) Programmable read only memory

Q.17 In a RS flip-flop no change occurs during.

a) Set mode                 b) reset mode
c) Disabled mode         d) prohibited mode

Q.18 Compounds of……………… are generally used for LED.

a) Sulphur                    b) silica
c) Phosphorus               d) gallium

Q.19 ……… family of logic circuits uses field effect transistors.

a) CMOS
b) TTL
c) Both ‘a’ and ‘b’
d) None of the above

Q.20 Power is drawn by a CMOS circuit only when

a) in static state
b) its output is height
c) its output is low
d) its switches logic levels

Q.21 GMOS circuits are extensively used for one-chip computers mainly because of their extremely……

a) high noise immunity
b) low power dissipation
c) low cost
d) large parching density

Q.22 …………… multivibrator can be used as a clock timer.

a) Astable
b) Bistable
c) Either of the above
d) None of these

Q.23 In a digital counter the number of flip-flops is

a) Always odd 
b) always even
c) Always 2
d) Equal to the number of bits required in the final binary count

Q.24 According to algebra of logic, (A+A) equals

a) 0                          b) 1
c) A                          d) A A

Q.25 Octal coding involves grouping the bits in

a) 3’ s                           b) 4’s
c) 5’s                            d) 7’s

Q.26 The binary division 110002+ 1002 gives…..

a) 11                            b) 101
c) 110                           d) 1100

Q.27 The number 178 is equivalent to binary

a) 111                          b) 1110
c) 1111                         d) 10000

Q.28 The output of a 2-input OR gate is zero only when its

a) Either input is 0      b) either input is 1
c) Both inputs are 0     d) both inputs are 1

Q.29    Which of the following 4-bit combinations (s) is/are invalid in the BCD code?

a) 0010                        b) 0101
c) 1000                       d) 1010

Q.30 The number 1001012 is equal to octal…

a) 25                            b) 37
c) 45                            d) 54

Q.31 A unique advantageous feature of CMOS logic family is its

a) Speed
b) Use of NMOS circuits
c) Dependence on frequency
d) Power dissipation is nanowatt range

Q.32 The two outputs of RS flip-flop are

a) Always high
b) Always low
c) Either low or high
d) Always complementary

Q.33 An A/D converted uses for reference purpose

a) a flip- flop
b) a saw tooth generator
c) d.c. voltage
d) set of keys

Q.34 ……. Converter can be used to change analog voltage to binary data.

a) A/D                          b) D/A
c) Both a & b               d) None of the above

Q.35 The number of full adders in a 4-bit parallel adder will be

a) tow                          b) three
c) four                         d) six

Q.36 Which  of the following binary additions is incorrect?

a) 1 + 1 = 0                  b) 0 + 1 = 1
c) 0 + 0 = 0                  d) 1 + 0 = 1

Q.37 ……. Is synchronous.

a) Full adder
b) Half adder
c) Clocked R-S flip-flop
d) R-S flip-flop

Q.38 A D-flip-flop is …….. Flip-flop.

a) Digital                     b) delayed
c) Dial type                   d) differential

Q.39 The output of basic DTL configurations is

a) high when all inputs are low
b) high when all inputs are high
c) low when all inputs are high
d) low when one of the inputs is high

Q.40 In Schottky TTL, a Schottky diode is used primarily to

a) act as a switch
b) act as a controlling switch
c) prevent saturation of the transistor
d) saturate the transistor

Q.41 Which of the following has a binary input?

a) D/A converter         b) A/D converter
c) Both a & b               d) None of the above

Q.42 Typical switching time for ECL is

a) 5 seconds                b) 5 milliseconds
c) 5 microseconds        d) 5 nanoseconds

Q.43 A Schottky diode has………… minority carriers and……. Voltage drops in forward direction.

a) no, very low            b) no, very high
c) large number of, very high
d) large number of, very low

Q.44 For 2-out-f 5 code which of the following statements is correct?

a) It has even parity
b) It is an unweighted code
c) It has exactly two 1’s in each code group
d) All of the above

Q.45 An ASCII input/output code is……. Bit code

a) Two                    b) four
c) Seven                  d) eight

Q.46    ………. Flip-flop is used as latch.

a) T                              b) D
c) JK                             d) RS

Q.47 Which of the following codes is used to reduce the error due to ambiguity in reading of a binary optical encoder?

a) Noise margin          b) Bandwidth
c) Gate dissipation      d) Propagation delay

Q.48 A gate in which all

a) BCD code                 b) Gray code
c) Octal code               d) Excess-3 code

Q.49 A gate in which all inputs must be low to get a high output is called

a) An AND gate            b) A NAND gate
c) An inverter              d) A NOR gate

Q.50 This of the following is the simplified versions of the Boolean expression AB + A B C + (A+B+C)?

a) A B + B C                 b) A B + B C
c) AB+ BC                    d) A B + B C

Q.50 For implementation of all functions of the basic logic functions, it suffices to have

a) NOT
b) ANDNOT
c) OR
d) None of the above

Q.51 The memory element antimagnetic film memory consists of

a) Doped aluminum
b) Plated wires
c) nickel Iron alloy
d) Superconductive material

Q.52 To solve differential equations numerically which of the following methods is used?

a) Newton-Raphson method
b) Gauss-elimination method
c) Runga-Kutta method
d) Any of the above

Q,53 …. Is used for storing binary information

a)A latch                  b) A register
c)A flip-flop              d) All of the above

Q.54 BCD expresses each decimal digit as

a) a byte                      b) a string of  bits
c) a string of 4 bits       d) a string of 2 bits

Q.55 The output states in sequential circuits are functions of

a) present and past input
b) presents input states
c) past input states
d) none of the above

Q.56 When a binary adder is used as BCD adder, the sum is correct when it is

a) Less than 9 
b) greater than 9
c) less than 16
d) none of the above

Q.57 During instructions execution read cycle is always followed by

a) delete signal           b) read cycle
c) write cycle             d) none of the above

Q.58 Schmitt trigger can be used as a

a) Flip-flop
b) Comparator
c) Square—wave generator
d) all of the above

Q.59 For digital ICs the most widely used ‘Bipolar Technology’ is

a) ECL
b) DTL
c) TTL
d) None of the above

Q.60 ……… circuit can be used as parallel to-series converter

a) Multiplexer             b) Digital counter
c) Decoder                  d) De- multiplexer

Q.61 A half adder has which of the following?

a) Two inputs and two outputs
b) Three inputs and two outputs
c) Two inputs and one output
d) One input and one output

Q.62 ……….. Flip-flop does not have race problem.

a) D                             b) T
c) JK                             d) Master-slave

Q.63 A ring counter is same as

a) A NAND gate           b) An AND gate
c) A NOR gate             d) An inverter

Q.64 The Schmitt trigger, for a sinusoidal input, gives output as

a) Sinusoidal itself       b) square wave
c) Saw tooth                d) None of the above

Q.65 …….. error can be usually deleted by a parity check.

a) One-bit                    b) Double-bit
c) Three-bit                 d) Any-bit

Q.66 BCD number are obtained by

a) Converting binary to decimal
b) Each decimal digit is represented by a four bit binary
c) Converting decimal number to binary
d) Converting decimal to octal numbers

Q.67 A BYTE stands for a string of ……….. BITS.

a) Two                          b) four
c) Eight                        d) twelve

Q.68 ……….. is an unweighted code

a) 63210                      b) 2421
c) 8421                 d) Excess-3code

Q.69 Semiconductor memories are

a) non-volatile, small size’
b) Volatile, small size
c) volatile
d) Non-volatile

Q.70 Due to which of the following reasons a NAND gate is called a universal logic element/

a) Many digital computers use NAND gates
b) All the minimizing techniques are applicable for optimum NAND gate realization
c) Any logic function can be realized by NAND gate alone
d) All of the above

Q.71 K- map method of simplification can only be applied when the given functions is in

a) Canonical form
b) Product of sum form
c) Sum of product form
d) Any of the above form

Q.72 In which of the following the power dissipation is the lowest?

a) ECL              b) MOS
c) TTL              d) None of the above

Q.73 Which of the following are the most widely used universal gates?

a) NAND and OR gates
b) NOR and AND gates
c) OR and AND gates
d) NOR and NAND gates

Q.74 As compared to analog computers, digital computers are more widely used because they are

a) Easier to maintain
b) Useful over wider ranges of problem types
c) Less expensive
d) Always more accurate & faster

Q.75 In a full adder, there are

a) Three binary digit inputs and three binary digit output
b) Three binary digit inputs and binary outputs
c) two binary number inputs and two outputs
d) none of the above

Q.76 Generally……… flip-flops are used in shift registers.

a) D                             b) T
c) SR                            d) JK

Q.77 In octal system the value of 25 is

a) 20                            b) 40
b) 200                          d) 400

Q.78 Which of the following circuits exhibits memory?

a) Ex. OR gate
b) NAND gate
c) Astable multivibrator
d) Bistable multivibrator

Q.79 A simple flip-flop is a ……. Bit storage cell.

a) One                         b) tow
c) Three                       d) four

Q.80 An AND gate is a ……… circuit.

a) Relaxation               b) memory
c) Sequential               d) combinational

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29-01-2016

TEST-2 (DIGITAL ELECTRONICS)-(EECTRONIC)

Q.1      …………………can provide a digital signal.

a) Variable resistor
b) Slow turning of a potentiometer
c) A cosine wave
d) A square wave

Q.2 The digital systems usually operate on……………..

a) hexadecimal system
b) octal system
c) binary system
d) decimal system

Q.3 Which of the following statements is correct regarding a pure sine wave?

a) It is a digital signal
b) It is a digital signal at higher frequencies
c) It is an analog signal
d) It is neither nor analog signal

Q.4 Boolean algebra is essentially based on…….

a) numbers                  b) truth
c) logic                    d) symbols

Q.5 In a digital signal the number of levels is

a) two                          b) four
c) six                          d) ten

Q.6 The binary system uses powers of ………..for positional values.

a) 2                              b) 4
c) 6                              d) 8

Q.7 In binary numbers, shifting the binary point the one place to the right

a) multiplies by 2        b) multiplies 4
c) divides by 4           d) increase by 2

Q.8 Binary 111 represent’s

a) decimal 4                b) decimal 7
c) decimal 8                d) decimal 222

Q.9 In binary system, decimal 1 can be written as

a) 0001                        b) 0010
c) 0100                        d) 1000

Q.10 After counting 1, 1, 10, 11 the next binary number is

a) 15                            b) 100
c) 110                          d) 120

Q.11 ………… is not an octal number

a) 15                            b) 19
c) 77                            d) 101

Q.12 Which of the following binary relations is invalid?

a) 1 + 1 = 0                  b) 0 X 0 = 0

c) 1 X 1 = 1                 d) 0 + 1 -= 1

Q.13 The cumulative addition of  the four binary bits (1+11+1) gives

a) 100                          b) 111
c) 1001                          d) 1111

Q.14 If decimal 10 in binary is 1010. Then decimal 100 in binary will be

a) 1111111                  b) 1100100
c) 1100100                  d) 1000100

Q.15 The binary equivalent of A16 is

a) 1000                        b) 1010
c) 1011                        d) 1110

Q.16 The number 10002 is equivalent to decimal number

a) four                         b) eight
c) sixteen                      d) one thousand

Q.17 Binary 111111 represents

a) decimal 51              b) decimal 63
c) decimal 87              d) decimal 99

Q.18 In binary system decimal 0.875 is represented by

a) 0.001                       b) 0.0101
c) 0.011                       d) 0.111

Q.19 In binary system decimal 10.75 is represented by

a) 10.1010                   b) 101.1110
c) 111.1111                 d) 1010.11

Q.20 Binary 1000 when subtracted from binary 1111, the result will be

a) 111  b) 1000
c) 1010         d) 1110

Q.21 The result of binary subtraction (100 – 001) is

a) 001                          b) 011
c) 111                          d) -111

Q.22 Due to which of the following main reasons the digital computers use complementally subtraction?

a) It avoids direct subtraction
b) It is a very simple process
c) It simplifies their circuitry
d) It can handle negative numbers easily

Q.23 BCD code is…………..

a) a binary code
b) an alphanumeric code
c) non-weighted
d) the same thing as binary numbers.

Q.24 A logic gate is an electronic circuit which

a) works on binary algebra
b) makes logic decisions
c) alternates between 0 and 1 values
d) allows electron flow only in one direction

Q.25 Binary 1000 will be the result of which of the following subtraction in binary system?

a) 11111-1110             b) 1011-1110
c) 1111-111               d) 1010-101

Q.26 Logic state 1, in positive logic, corresponds to

a) zero voltage

b) lower voltage level
c) positive voltage
d) higher voltage level

Q.27 Logic state 1, in negative logic, corresponds to

a) zero voltage
b) lower voltage level
c) negative voltage
d) more negative voltage

Q.28    For AND gate the Boolean expression is

a) A = B                       b) A + B = y

c) A – B ≠ Y                d) A . B = Y

Q.29 A+B=Y is the Boolean expression for which of the following?

a) NOR gate                b) AND gate

c) XNOR gate              d) None of the above

Q.30 An XOR gate produces an output only when its two inputs are…….

a) same                        b) different
c) low                          d) high

Q.31 In Boolean algebra different variables used can have values of

a) true or false
b) low or high
c) ON or OFF
d) 0 or 1

Q.32 For getting an output from an XNOR gate, its both inputs must be……………

a) at the same logic level
b) at the opposite logic level
c ) high
d) low

Q.33 ……. Gate is formed by inversion of the output of the AND gate.

a) XNOR                      b) NOR
c) OR                        d) NAND

Q.34    ……. Gate corresponds to the action of parallel switches

a) NAND                       b) NOR
c) OR                           d) NAND

Q.35 A NOR gate is ON only when all its inputs are

a) OFF                          b) ON
c) positive                    d) high

Q.36 A combination of AND function and NOT function will results in ………. Gate

a) NAND                      b) AND
c) XNOR                      d) NOR

Q.37 A = A is the Boolean expression for

a) multiplier                b) inverter
c) adder                       d) subtract or

Q.38 ………..logic function has the output low only when both inputs are high

a) NOR                        b) OR
c) AND                         d NAND

Q.39 The dual of the statement (A + 1 ) = 1 is

a) A + A = A                 b) A . 1 = A
c) A . A = 1                 d) A. 0 = 0

Q.40 In Boolean algebra , 1 + A + B + C is equal to

a) 1 + 3A                      b) 1 + A
c) A                              d) 1

Q.41 The radix for binary system is

a) 10                            b) 2
c) 1                              d) 0

Q.42 In Boolean algebra, A+ A + A + …….+ A is the same as

a) zero                         b) A
c) nA                            d) An

Q.43 In a certain 2- point logic gate, when A = 0 , B = 0 and C = 1 , it must be……….

a) NOR gate    b) XOR gate
c) AND gate     d) NAND gate

Q.44 Integrated circuit logic gates contain the properties of

a) diodes
b) bipolar junction transistors
c) resistors
d) all of the above

Q.45 Saturated logic circuits have inherently….

a) higher power dissipation
b) low switching speed
c) short saturation delay time
d) none of the above

Q.46 The abbreviation TTL stands for

a) Transistor-transistor logic
b) Transistor-transistor logic
c) Transistor- transistor logic
d) Tuned transistor logic

Q.47 IGFET stands for

a) Insulated gate field effect transistor
b) Integrated gain field effect transistor
c) Infinite gain field effect transistor
d) Imaginary grid field effect transistor

Q.48 DTL stands for

a) Delayed tracking logic
b) Diode transistor logic
c) Digital timing logic
d) Dynamic transient logic

Q.49 The basic DTL configuration is…. Gate.

a) OR                        b) NOR
c) NAND                      d) AND

Q.50 The basic circuit configuration for TTL resembles that of a ……. Gate.

a) OR                           b) NOR
c) AND                         d) NAND

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TEST-1 SEMICONDUCTOR PHYSICS AND DIODES(ELECTRONICS)

Q.1 Nucleus is made of

a) electrons and protons
b) photons and neutrons
c) photons and neutrons
d) photons and electrons

Q.2 Atom of any element

a) positively charged
b) negatively charged
c) positively or negatively charged
d) not charged

Q.3 Conduction of electricity through conductor takes place by

a) protons
b) neutrons
c) bound electrons
d) free electrons

Q.4 Intrinsic semiconductor at room- temperature will have,………… available for conduction.

a) electrons
b) holes
c) both electrons and holes
d) none of the above

Q.5 Intrinsic semiconductor at d0’K will have ………..available for conduction.

a) electrons
b) holes
c) both electrons and holes
d) nothins

Q.6 At room temperature N- type material will have……..

a) more of electrons
b) more of electrons
c) equal number of electrons and holes

Q.7 At room temperature P-type material will have…………..

a) more of electrons
b) more of electrons
c) equal number of electrons and holes

Q.8 It is easy to break the covalent bond by thermal energy in case of……..

a) carbon                     b) germanium
c) silicon

Q.9 One eV of energy is equivalent to

a) 2.0 ers
b) 1.0X 10-19 joule
c) 0.16X10-19 joule
d) 3.14X10-19 joule

Q.10 Which of the following statements is incorrect regarding valence band in a solid?

a) It may be empty in some solids
b) It is the highest occupied band
c) It is either completely filled or partially filled
d) It represents the energy possessed by its valance electrons

Q.11 Which of the following statements is incorrect regarding conduction band?

a) It lies below the valence band
b) It may be either empty or partially filled
c) It is lowest unfilled energy band
d) It represents the energy of conduction electrons.

Q.12 The neighboring atoms in the crystalline lattice structure of a semiconductor like germanium form……. Bonds.

a) molecular   b) ionic
c) covalent      d) metallic

Q.13 The forbidden band in germanium at 00 K is

a) 0.03 eV        b) 0.785eV
c) 1.5 eV          d) 2.0 eV

Q.14 Donor type semi-conductor is formed by adding impurity of……….. valence.

a) 2                  b) 3
c) 4                  d) 5

Q.15 Fermi level represents the energy level with probability of its occupation of

a) zero              b) 25 percent
c) 50 percent   d) 100 percent

Q.16 Intrinsic semiconductors are those

a) which are made of semiconductor material in its purest form
b) which have zero energy gap
c) which have more electrons than holes
d) which are available locally

Q.17 The diffusion current is proportional to

a) applied electric field
b) square of applied electric field
c) concentration gradient of charge carrier
d) a constant value given by Fermi level

Q.18 The depletion region of a P-N junction is one that is depleted of

a) immobile charges
b) mobile charges
c) atoms

Q.19 Consider the energy level diagram of an intrinsic semiconductor. The Fermi level lies in the

a) valence band
b) forbidden gap
c) conduction band or
d) it can be at any of the above locations depending upon the doping concentratopm and temperature.

Q.20 In any specimen the Hall voltage is proportional to magnetic field B as

a) β                           b) β2
c) 1/β                       d) 1/β2

Q.21 Intrinsic concentration of charge carriers in a semiconductor varies as

a) T3                  b) T2
c) T                              d) 1/T

Q.22 The dynamic resistance of a diode varies as

a) I the current            b) I2
c) 1/I                            d) 1/I2

Q.23 At higher forward voltages, a junctions diode is likely to…..

a) become noisy
b) burn out
c) get saturated
d) suffer breakdown

Q.24 For converting intrinsic semiconductors into extrinsic ones, the level of doping required is about……

a) 1 : 102                     b) 1 : 104
c) 1 : 108                     d) 1 : 1016

Q.25 A pure semiconductor behaves like an insulator at 00 K because

a) there is no recombination of electrons with holes
b) drift velocity of free electrons is very small
c) free electrons are not available for current conduction
d) energy possessed by electrons at that low temperature is almost zero

Q.26  ……………. Is used to describe the static V/I characteristic of a junction diode

a) Bolzmann diode equation
b) Richardson-Dushman equation
c) Child’s Three half-power law
d) Einstein’s photoelectric equation

Q.27 The energy gap is much more in silicon than in germanium because

a) it has less number of electrons
b) it has high atomic mass number
c) its crystal has much stronger bonds called ionic bonds
d) its valence electrons. Are more tightly bound to their parent nuclii

Q.28 Which of the following statements is incorrect?

a) No electrons can occupy states in the forbidden gap
b) The forbidden band in silicon at 00K is 1.21 eV
c) Doping of a semiconductor results in creation of new energy band
d) Doping of semiconductor results in creation of new energy level in forbidden band

Q.29 Geranium atom contains

a) four neutrons
b) two protons
c) four electrons
d) two electron orbits

Q.30 Which of the following is a semiconductor?

a) Diamond
b) Arsenic
c) Phosphorous
d) Gallium arsenide

Q.31 Which of the following elements belong to the same group of periodic tables as that of silicon and germanium?

a) Phosphorous           b) Carbon
c) Sodium                    d) Boron

Q.32  In a atom the outermost orbit cannot have

a) less that four electrons
b) more than eight electrons
c) electrons of other atoms
d) all of the above

Q.33 When n is the number of the shell, the maximum number of electrons in the shell can be

a) n4               b) 2n3
c) 2n2              d) 2n

Q.34  A semiconductor has……………. Temperature co-efficient of resistance

a) zero                         b) positive
c) negative

Q.35 The atomic number of germanium is

a) 4                              b) 8
c) 16                            d) 32

Q.36 An electron will not contribute to electric current when

a) it is in a completely filled band
b) it strikes a positive ion
c) it loses its charge
d) it is at higher temperatures

Q.37  A semiconductor in its purest form is called.

a) insulator
b) superconductor
c) superconductor
d) extrinsic semiconductor

Q.38  The process of deliberately adding impurities to a semiconductor is known as….

a) drifting                    b) doping
c) sintering                  d) intrusion

Q.39   The temperature co-efficient of an intrinsic semiconductor is

a) zero             b) positive
c) negative

Q.40  The temperature co-efficient of an extrinsic semiconductor is

a) zero
b) positive
c) negative
d) none of the above

Q.41  As the temperature co-efficient of an intrinsic semiconductor is in crease

a) energy of the atoms is increased
b) more holes are created in the conduction band
c) holes and free electrons get fused together
d) none of these

Q.42  The conduction band

a) is always above the forbidden energy level
b) is the region of free electrons
c) concentrates holes for the flow of current
d) is a range of energies corresponding to the energies of the free electrons

Q.43  An electron in the conduction band

a) is always charge less
b) has tendency to leave the atom
c) has lower energy than an electron in the valence band
d) has higher energy’ than an electron in the valence band

Q.44  An intrinsic semiconductor at absolute zero

a) becomes extrinsic semiconductor
b) behaves like an insulator
c) disintegrates into pieces
d) becomes superconductor

Q.45  When an electron breaks a covalent bond and moves away

a) a vacancy is created in the broken covalent bond
b) more ions are produced
c) the semiconductor becomes conductor
d) the conductivity of the material increases

Q.46  A doped semiconductor is also known as

a) intrinsic semiconductor
b) extrinsic semiconductor
c) diffused semiconductor
d) none of the above

Q.47  A P-type semiconductor results when

a) a pent valet impurity is added to an intrinsic semiconductor
b) a trivalent impurity is added to an intrinsic semiconductor
c) either a pentavalent or trivalent impurity is added to an intrinsic semiconductor
d) none of the above

Q.48  The movement of a hole results from

a) excitation due to high temperature

b) change in number of protons in the atomc) the vacancy filled by valence electron from the neighboring atom
d) none of these

Q.49    ……………. Has the highest mobility.

a)Electron             b) Positive ions
a)Negative ions        d) Neutron

Q.50    The donor impurity must have only…………… valence electrons.

a) tow                          b) three
c) four                         d) five

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