ELECTRONIC SCIENCE
PAPER – II
Note : This paper contains fifty (50) objective type questions of two (2) marks each. All questions are compulsory.
1. The depletion region in a junction diode contains charges that are :
(1) Mobile donor and acceptor ion
(2) Fixed donor and acceptor ion
(3) Mostly majority carriers
(4) Mostly minority carriers
2. For the circuit shown below, the value of RL and maximum power are :
(1) 6 Ω and 0.51 W
(2) 12 Ω and 0.6 W
(3) 12 Ω and 0.75 W
(4) cannot be calculated without knowing RL
3. In a full wave rectifier, the current in each of the diode flows for :
(1) Half cycle of input signal
(2) Full cycle of input signal
(3) Quarter cycle of input signal
(4) Three fourth cycle of input signal
4. The Boolean SOP expression obtained from the truth table is :
(1) ABC’+A’BC
(2) AB’C+ABC’
(3) A’B’C+ABC’
(4) A’BC’+AB’C
5. Which command word of 8251 indicates enter hunt mode ?
(1) D0
(2) D1
(3) D6
(4) EH or D7
6. Consider the ‘C’ statement printf (“%f”,(float) 7/5); It prints :
(1) 1.0
(2) 1.4
(3) 2.0
(4) None of the above
7. The induction and radiation fields of an oscillating dipole becomes approximately equal at a distance ‘R’. The value of ‘R’ is :
(1) λ/6
(2) λ/4
(3) λ/3
(4) λ/2
8. The ability of a receiver to discriminate against the interfering signals is known as :
(1) Selectivity
(2) Sensitivity
(3) Fidelity
(4) Distortion
9. An LED made of GaAs operates at a wavelength of 0.86 μm, The surrounding medium is air.
The relative permittivity of GaAs is 12.9. The external quantum efficiency of the LED is :
(1) 2.31 %
(2) 23.1 %
(3) 13.1%
(4) 1.31 %
10. Sensitivity of potentiometer can be increased by :
(1) Decreasing the length of potentiometer wire
(2) Increasing the length of potentiometer wire
(3) Decreasing the current in potentiometer wire
(4) Decreasing the resistance in the rheostat in the series with the battery
11. The operation of JFET involves mainly :
(a) Flow of Minority carriers
(b) Flow of Majority carriers
(c) A very high input impedance
(d) Negative resistance
Which of the following is correct ?
(1) (b) and (c)
(2) (a) and (b)
(3) (c) and (d)
(4) (c) and (a)
12. Consider the following statements :
(a) Tellegen’s theorem is applicable to any lumped networks
(b) The reciprocity theorem is applicable to linear bilateral networks
(c) Thevenin’s theorem is applicable to two – terminal linear active networks
(d) Norton’s theorem is applicable to two – terminal linear active networks
Which of the above statements are correct ?
(1) (a), (b) and (c) only
(2) (a), (b) and (d) only
(3) (a), (b), (c) and (d)
(4) (b), (c) and (d) only
13. The addition of two binary variables A and B results into a SUM and a CARRY output.
Consider the following expressions for SUM and CARRY outputs.
Which of the following expressions are correct ?
(1) (a) and (c)
(2) (b) and (c)
(3) (d) and (b)
(4) (a) and (d)
14. What are the names of 16 – bit registers in 8085 ?
(a) SP
(b) PC
(c) Accumulator
(d) W
Options :
(1) (a) and (b) are correct
(2) (c) and (d) are correct
(3) (a), (b) and (c) are correct
(4) (b), (c) and (d) are correct
15. Consider the following ‘C’ Program :
Which of the following statements are correct : about the ‘C’ program given above ?
(a) The code is correct and runs successfully
(b) The code is erroneous since the statement declaring array is invalid
(c) The code is erroneous since the subscript for array used in ‘for’ loop is in the range 1 to max – 1
(d) The code is erroneous since the type declaration statement int a [max]; is done after scanf()
Options :
(1) (a) and (c)
(2) (b) and (c)
(3) (b) and (d)
(4) (c) and (d)
16. The radiation pattern of two non – directional radiators fed with equal currents (with a phase shift) shown in figure belongs to :
(a) d = λ/2 (b) α = –90°
(c) d = λ/4 (d) α = 0°
(1) (a) and (b) are correct
(2) (b) and (c) are correct
(3) (c) and (d) are correct
(4) (a) and (d) are correct
17. An FM detector produces a peak – to – peak output voltage of 1.2 V from an FM signal that is modulated to 10 kHz deviation by a sine wave.
(a) The peak voltage is 0.6V
(b) The detector sensitivity is 6 μV/Hz
(c) The peak voltage is 2.4V
(d) The detector sensitivity is 60 μV/Hz
Which of the above are correct ?
(1) (a) and (b)
(2) (b) and (c)
(3) (c) and (d)
(4) (a) and (d)
18. In the following circuit of buck – boost regulator :
Input voltage=12V, duty cycle=0.25 and switching frequency=25 kHz , L=125 μH and C=220 μF. The average load current = 1.25A. Following statements are given :
(a) Average output voltage = 4.8 V
(b) Peak to peak output ripple voltage = 5.68 V
(c) Average output voltage =−4 V
(d) Peak to peak output ripple voltage = 56.8 mV
Which one is correct option :
(1) (a) and (b)
(2) (b) and (c)
(3) (c) and (d)
(4) (a) and (d)
19. Consider the following statements regarding the steady – state error due to a step function input.
(a) Type ‘0’ system 
(b) Type ‘0’ system ess = 0
(c) Type ‘1’ system ess = 0
(d) Type ‘1’ system ess =∞
Which of the above statements are correct ?
(1) (a) and (b)
(2) (b) and (c)
(3) (a) and (c)
(4) (a) and (d)
20. The Q point of a voltage amplifier is selected in the middle of the active region because :
(a) In this case it requires a small dc voltage
(b) The operating point becomes stable
(c) It gives distortion less output
(d) It is suitable for small input signals without distorted output
Which of the following is correct ?
(1) (b) and (d)
(2) (c) and (d)
(3) (a) and (d)
(4) (b) and (a)
21. Match the following list :
22. Match the following list :
23. Match the following list :
24. Match the following list :
25. Match the following list :
26. Match the following list :
27. Match the following lists in terms of directivity of the antennas :
28. Match the following list :
29. Match the following list :
30. Match the following list :
31. The correct sequence of TTL logic chip in decreasing order of their gate delay time is :
(a) 74 L 00
(b) 74 S 00
(c) 74 LS 00
(d) 74 H 00
Code :
(1) (a), (b), (c), (d)
(2) (a), (c), (d), (b)
(3) (a), (c), (b), (d)
(4) (b), (a), (d), (c)
32. Following are the incident radiation used for lithography while making integrated circuit (depending upon the feature size).
(a) Visible light
(b) Electron beam
(c) Ion beam
(d) UV light
Sequence the radiation used for increasing order of the feature size :
Code :
(1) (c), (b), (d), (a)
(2) (b), (a), (d), (c)
(3) (a), (b), (c), (d)
(4) (a), (d), (b), (c)
33. Which of the following is correct sequence of evaluation for the ‘C’ expression given below ?
R=A+B*R/4%2−1 ;
(1) −% / *+=
(2) / * % −+=
(3) * / % −+=
(4) * / % +−=
34. Arrange the following in terms of theoretical attenuation in ascending order for a distance of 100 ft from the transmitter.
(a) Ku band
(b) X band
(c) L band
(d) S band
The correct sequence of attenuation in ascending order is :
Code :
(1) (c), (d), (b), (a)
(2) (a), (b), (c), (d)
(3) (a), (b), (d), (c)
(4) (d), (b), (c), (a)
35. Consider the following circuit models.
(a) Integrator
(b) Proportional + Derivative
(c) Proportion + Integral + Derivative
Arrange the above circuit models in decreasing order of their circuit complexity :
Code :
(1) (a), (b), (c)
(2) (a), (c), (b)
(3) (b), (a), (c)
(4) (c), (b), (a)
Directions : Question No. 36 to 45 :
The following items consist of two statements, one labelled as “Assertion (A)” and the other labelled as the “Reason (R)”. You are to examine the two statements carefully and decide if theAssertion (A) and the Reason (R) are individually true and if so whether the reason is a correct explanation of the assertion. Select your answer to these items using the code given below and mark your answer accordingly.
Code :
(1) Both (A) and (R) are true and (R) is the correct explanation of (A)
(2) Both (A) and (R) are true, but (R) is not the correct explanation of (A)
(3) (A) is true, but (R) is false
(4) (A) is false, but (R) is true
36. Assertion (A) : Tunnel diode characteristics have negative resistance region.
Reason (R) : Tunnel diode can be used as rectifier.
37. Assertion (A) : Q factor of a series resonant circuit is 
Reason (R) : High Q means better selectivity.
38. Assertion (A) : For making integrated circuit the type of lithography chosen depends upon the feature size.
Reason (R) : UV lithography can easily be used for making nano size circuits.
39. Assertion (A) : In a parallel – in – serial out shift register data is loaded one bit at a time.
Reason (R) : A serial – in – serial out shift register can be used to introduce time delay in the circuits.
40. Assertion (A) : Architecturally 8086 μp is totally different from its predecessor 8085 μp but functionally it is downward compatible with 8085.
Reason (R) : The segmented architecture was introduced in 8086 μp to keep compatibility with 8085 μp.
41. Assertion (A) : If ‘char a[10];’ is defined in one file and ‘extern char *a;’ is declared in another file then it does not work.
Reason (R) : The declaration ‘extern char *a;’ does not declare an array and therefore does not match the actual definition.
42. Assertion (A) : A high electron mobility transistor is based upon modulation doped (GaAs – Al GaAs) single heterojunction structure.
Reason (R) : HEMT shows very high noise figure and very low gain at very high microwave frequencies upto 70 GHz.
43. Assertion (A) : Shot noise is due to random variations in current flow in active devices.
Reason (R) : Current is a flow of carriers each of which carries a finite amount of charge.
44. Assertion (A) : In a two transistor model the anode current is given by :
Reason (R) : The regenerative or Latching action due to a positive feedback is demonstrated in a two transistor model of a thyrister. It contains a pnp & a npn transistors.
45. Assertion (A) : The closed loop pole – zero dipole introduced by PI controller does not contribute significantly to the transient response of the closed loop system.
Reason (R) : The PI controller adds a pole at s = 0 and a zero at s =−z to the closed loop transfer function.
Based on the following para, answer Q. No. 46 to 50 :
Antennas are used to transmit and receive signals. The basic theory behind them is given by Maxwell’s equations and electromagnetics. Its size depends upon the frequency used. Higher is the frequency lower are the dimension of antennas. Antennas are of various types, like resonant, non – resonant etc. They are different for different applications.
46. If ‘Z’ is the impedance of a simple dipole, the impedance of ‘n’ fold dipole is given by :
(1) n Z
(2) n2 Z
(3) Z/n
(4) Z/n2
47. The directivity of a small loop and a short dipole has the following ratio :
(1) 2 : 1
(2) 1 : 2
(3) 1 : 1
(4) 1 : 4
48. Patch is a :
(1) High gain wide band antenna
(2) High gain narrow band antenna
(3) Low gain narrow band antenna
(4) Low gain wide band antenna
49. The maximum gain for H – plane sectoral horn with slant length of 12 λ occurs when aperture width is :
(1) λ
(2) 3 λ
(3) 6 λ
(4) 12 λ
50. Helical antennas are often used for satellite tracking in VHF range because of :
(1) Troposcatter
(2) Super – refraction
(3) Ionospheric refraction
(4) Faraday effect
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