ELECTRONICS (PREVIOUS SET QUESTIONS)

 Electronics

  Semiconductor devices (diodes, junctions, transistors, field effect devices, homo and hetero- junction devices). Transistor amplifiers and oscillators, device structure, device characteristics, frequency dependence and applications. Opto-electronic devices (solar cells, photo-detectors, LEDs). Operational amplifiers and their applications. Digital techniques and applications (registers, counters, comparators and similar circuits). A/D and D/A converters. Microprocessor and microcontroller basics. Data interpretation and analysis. Precision and accuracy. Error analysis, propagation of errors. Least squares fitting.

PREVIOUS YEAR QUESTION PAPER

SET 2019/7

61. The registers used in pocket calculators are -

A) Shift register    B) Static shift register   C) Buffer shift register     D) Dynamic MOS

64 Asynchronous counters are also known as:

A) Decade counter B) Multiple clock counter    C) Ripple counter D) Modulus counter

90. The minimum number of flip-flops required for a mod-12 ripple counter is:

A) 3       B) 4        C) 6        D) 12

101. For a p-n junction formed by heavily doped n-and p-type semiconductors which among the

following is TRUE?

A) depletion region will be wider

B) depletion region will be narrower

C) width of depletion region is independent of level of doping

D) none of these

102. Potential barrier at a p-n junction is typically about ---------.

A) 10 -20 eV B) 2-3 eV C) 0.1-0.3 eV D) 5-10 eV

103. The atomic bond is Si and Ge are --------.

A) ionic bonds B) coordinate bonds

C) van der Waal’s bonds D) covalent bonds

104. Knee voltage for p-n junction diode made using an indirect band gap semiconductor is

0.3 eV. The semiconductor used is --------.

A) GaAs B) GaSb C) Si D) Ge

105. Approximate equivalent circuit of a p-n junction diode is -------.

A) a switch in series with a battery and a resistor

B) a battery in series with a capacitor

C) a resistor in series with a capacitor

D) none of these

109. The self destruction of an unstabilised transistor is known as --------.

A) avalanche break down B) zener break down

C) thermal runaway D) peak depreciation

110. A Si transistor has ICBO = 0.02 μA at 27°C. The leakage current doubles for every 6°C rise

in temperature. Find the base current at 57°C when the emitter current is 1 mA. Given

α = 0.99

A) 94μA       B) 9.4mA    C) 9.4μA     D) 0.94mA

111. 2’s complement of a binary number is obtained by -------.

A) adding 1 to its 1’s complement

B) by replacing 0s by 1 and 1s by zeros

C) adding 2 to its 1’s complement

D) adding 1 to it

112. In Asynchronous counters, --------.

A) Flip flops are connected in parallel

B) Clock pulses are simultaneously applied to all flip flops

C) Flip flops are connected in series and Clock pulses are simultaneously applied to all

flip flops

D) None of these

113. According to Boolean algebra AC + ABC = --------.

A) AC         B) ABC  C) AB    D) A+B

114. When a large step input voltage is applied to OP AMP 741, the output voltage changes

from 0 to 10 V in 20 microseconds. Slew rate of the OPAMP is -----.

A) 10μS       B) 20μS     C) 0.5V/μS          D) 0.5V

115. In an OPAMP integrator, the feedback is through -------.

A) resistor      B) diode C) capacitor      D) inductor

SET 2019/2

27. Colour of a Light Emitting Diode (LED) depends on

A) Applied biasing voltage

B) Nature of the material used

C) Recombination rate of charge carriers

D) All the above

30. The dominant mechanism for the motion of charge carriers in forward and reverse

biased silicon p-n junction are

A) drift in forward bias and diffusion in reverse bias

B) diffusion in forward bias and drift in reverse bias

C) diffusion in both

D) drift in both

61. Which of the following describe an n type semiconductor?

A) Neutral B) positively charged   C) negatively charged   D) has many holes

62. What causes depletion layer?

A) doping B) recombination  C) barrier potential D) ions

63. In a common base amplifier the phase difference between the input signal voltage and  output signal voltage is

A) 0 B) π/4 C) π /2 D) π

64. To reduce the distortion of an amplified signal we can increase the

A) collector resistance     B) emitter feedback resistance 

C) generator resistance       D) load resistance

65. Which of the following is true related with a JFET?

A) voltage controlled device      B) current controlled device

C) has low input resistance       D) has very large voltage gain

66. The pinching voltage of JFET has the same magnitude as the

A) gate voltage              B) drain source voltage

C) gate source voltage    D) gate source cut off voltage

67. If the peak output voltage of full wave bridge rectifier is Vm,, its no-load output dc voltage is:

B) 2 Vm/pi

68. An Op-Amp can amplify

A) ac signal B) dc signal  C) both ac and dc signals D) neither ac nor dc signals

69. Minimum number of NOR Gates required to construct an AND Gate is

A) 3 B) 4 C) 2 D) 6

70. Which of the following is not true about LED?

A) spontaneous emission B) incoherent light

C) low current density D) high modulation bandwidth

71. The efficiency of a photo detector is directly proportional to

A) photocurrent B) incident optical power    C) charge generated D) none of these

72. The biasing state of a solar cell is

A) unbiased B) forward biased  C) reverse biased D) either B or C

73. The number of flip-flops required to design a mode-6 counter is

A) 5 B) 6 C) 2 D) 3.

74. The resolution of an ADC is 3, then the number of possible states is

A) 3 B) 2 C) 6 D) 8

75. The register that stores the address of the instructions to be executed in a

microprocessor is

A) IP B) SP C) IR D) SR

76. Two resistances (60±2) Ω and (120±4) Ω are in series, then the percentage error in the combination is

A) 3.3 B) 6 C) 2 D) 8

77. Fermi level of an intrinsic semiconductor is

A) near conduction band minimum      B) near valence band maximum

C) at center of forbidden energy gap    D) none of the above

78. A common source FET amplifier has a load resistance of 500 kΩ, ac drain resistance of 100 kΩ and amplification factor 24, then its voltage gain is

A) 10 B) 20 C) 30 D) 40

79. A shift register that has both serial and parallel input and output is

A) universal shift register B) bidirectional shift register

C) shift register counter D) none of the above

80. For a transistor in CE configuration Vcc is 18 V, Vbb is 6 V, current gain is 75, Ico is  100 μA, Rc is 1 kΩ and Vce is 9 V. Then the base current in mA is

A) 0.12 B) 12 C) 1.2 D) 120