ELECTRONIC SCIENCE
Paper – II
Note : This paper contains fifty (50) objective type questions of two (2) marks each. All questions are compulsory.
1. For the circuit shown in figure, the terminal voltage Vab is given by :
(A) 5 V
(B) 6 V
(C) 2.5 V
(D) 3 V
2. The earth has a conductivity of 10–2 mho/m, ∈r = 10, μr = 2, f = 10 GHz, the earth behaves like a
(A) Good conductor
(B) Moderate conductor
(C) Good dielectric
(D) Bad dielectric
3. The carrier velocity in a silicon p-i-n photodiode with 25 μm depletion layer width is 3 × 104 m/s. The
maximum response time for the pin diode is given by :
(A) 52 ns
(B) 2.5 ns
(C) 62 ns
(D) 5.2 ns
4. For a JFET, above the pinch-off voltage, as the drain voltage increases, the
(A) the drain current remains constant.
(B) the drain current decreases.
(C) the drain current increases linearly.
(D) the drain current varies parabolically.
5. What bandwidth is needed for an FM signal that has a peak deviation of ± 3 KHz and handles audio signals from 200 Hz to 5 KHz ?
(A) 6 KHz
(B) 16 KHz
(C) 10 KHz
(D) 9.6 KHz
6. In which of the following base system, 132 is not a valid number ?
(A) Base 16
(B) Base 10
(C) Base 8
(D) Base 2
7. What is the relation between k and T such that a unity feedback control system whose open loop transfer
function below is stable :
(A) 0 < k < 10T
(B) 0 > k > 10T
(C) 0 < k < T
(D) 0 < k > T
8. Microprocessor development had happened because of LSI. What is LSI ?
(A) Large Scale Integral
(B) Large Signal Integration
(C) Large Scale Integration
(D) Long Signal Integration
9. ‘Stdio.h’ header file contains functions related to
(A) prototypes for the standard input/output library functions.
(B) prototypes for the standard input and standard output functions.
(C) prototypes for the functions that perform input from files.
(D) prototypes for functions that perform input from strings in memory and outputs to strings in memory.
10. The threshold voltage of a MOSFET can be lowered by
1. using a thinner gate oxide
2. reducing the carrier concentration in the substrate
3. increasing the carrier concentration in the substrate
Of these statements :
(A) 3 alone is correct.
(B) 1 and 2 are correct
(C) 1 and 3 are correct
(D) 2 alone is correct
11. An angular position to be measured using a transducer. Which of the following types of transducers can be used for this purpose ?
1. Circular potentiometer
2. LVDT
3. E-pick off
4. Synchro
Select the correct answer using the codes given below :
Codes :
(A) 1, 2, 3 and 4
(B) 2 and 3
(C) 1, 2 and 4
(D) 1 and 4
12. In a hybrid TEE (Magic T), following statements are given :
1. S11, S22, S33 and S44 are nonzero.
2. All junctions are reciprocal i.e. Sjk = Skj
3. S11, S22, S33 and S44 are zero.
4. S13 = –S23, S14 = S24, S43 = 0 and S34 = 0
Which one of the following is true ?
(A) 1, 2 and 4 are correct.
(B) 1 and 2 are correct.
(C) 2, 3 and 4 are correct.
(D) 1, 2 and 3 are correct.
13. In optical fibers, following statements are given :
1. 1550 nm is zero dispersion wavelength
2. 1330 nm is zero dispersion wavelength
3. At 1330 nm, attenuation is minimum
4. At 1550 nm, attenuation is minimum
Which one of the following is correct ?
(A) 1 and 4 are true.
(B) 1 and 3 are true.
(C) 2 and 4 are true.
(D) 1, 2 and 3 are true.
14. Which of the following techniques are used to generate frequency modulated signal :
1. Armstrong
2. Foster-Sealy Discriminator
3. Balanced Modulator
4. Reactance Modulator
Which one of the following is true ?
(A) 1 and 2
(B) 1, 2 and 3
(C) 1 and 3
(D) 1 and 4
15. Which of the following statements are true regarding the operation of JK flip-flop ?
1. When K input is low and J input is high, the Q output of the flip flop is reset.
2. When K input is high and J input is low, the output Q of the flip flop is set.
3. When both the inputs K and J are low, the output Q does not change.
4. When both the inputs K and J are high it is possible to set or reset the flip-flop (ie) the output toggle on next positive clock edge.
Which one of the following is true ?
(A) 1 and 2
(B) 3 and 4
(C) 1, 2 and 3
(D) All of the above
16. A linear two-terminal network can be replaced by an equivalent circuit consisting of a current source in
parallel with resistor RN, where RN is the ratio of
1. Closed circuit voltage to short circuit current at the terminal pair.
2. Open circuit voltage to open circuit current at the terminal pair.
3. Open circuit voltage to short circuit current at the terminal pair.
4. Closed circuit voltage to open circuit current at the terminal pair.
(A) 1 and 4
(B) only 2
(C) 3 only
(D) only 3 and 4
17. The following signals of microprocessors are intercepts :
(A) 1 and 3
(B) 1 and 4
(C) 2 and 3
(D) 3 and 4
18. C programming language can be considered as
1. Low level programming
2. High level programming
3. Assembly level programming
4. Machine level programming
(A) 1 and 4
(B) 2 and 3
(C) 1 and 2
(D) 3 and 4
19. A linear two terminal circuit can be replaced by an equivalent circuit consisting of a voltage source Vt in series with a resistor Rt where Rt is the ratio of
1. open circuit voltage to the short circuit current at the terminal pair.
2. short circuit current to the short circuit voltage at the terminal.
3. Open circuit voltage to the open circuit current at the terminal pair.
4. the independent sources are turned off.
(A) 1 and 4
(B) 2 and 4
(C) 3 and 4
(D) 2 and 3
20. Semi conductors have
(A) Positive temperature coefficient of resistance
(B) Zero temperature coefficient of resistance
(C) Negative temperature coefficient of resistance
(D) Resistance does not change with temperature
21. Consider the following Excimer Lasers used for photolithography and surgery purposes :
1. Ar2 Excimer laser
2. ArF Excimer laser
3. XeCl Excimer laser
4. XeF Excimer laser
The correct sequence of the descending order of wavelength of operation is
(A) 2, 3, 1, 4
(B) 1, 2, 3, 4
(C) 1, 3, 2, 4
(D) 4, 3, 2, 1
22. Arrange the following communication systems in increasing order of their available commercial bandwidth :
1. Satellite Communication System
2. Amplitude Modulated System
3. Frequency Modulated System
4. Two-line transmission system
Correct sequence is
(A) 4, 2, 3, 1
(B) 1, 2, 3, 4
(C) 4, 3, 2, 1
(D) 1, 3, 2, 4
23. Priority of the interrupts in the order from the highest to least priority
The correct sequence is
(A) 1, 4, 2 and 3
(B) 3, 1, 4 and 2
(C) 2, 4, 1 and 3
(D) 3, 2, 4 and 1
24. Sequence of operators according to the priority
1. ‘/’
2. ‘+’
3. ‘*’
4. ‘–’
The correct sequence is
(A) 1, 2, 3 and 4
(B) 2, 3, 4 and 1
(C) 3, 4, 1 and 2
(D) 3, 1, 2 and 4
25. What is the correct sequence of the following step in the fabrication of a monolithic, bipolar junction transistor ?
1. Emitter diffusion
2. Base diffusion
3. Buried layer formation
4. Epi-layer formation
Select the correct sequence using the codes given below :
(A) 3, 4, 1, 2
(B) 4, 3, 1, 2
(C) 3, 4, 2, 1
(D) 4, 3, 2, 1
26. Match List – I with List – II and select the correct answer using codes given below :
Directions : Q. Nos. 36 to 45 : The following items consists of two statements, one labelled the “Assertion (A)” and the other labelled the “Reason (R)”. You are to examine these two statements carefully and decide if the Assertion (A) and 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 codes given below and mark your answer accordingly.
Codes :
(A) Both (A) and (R) are true and (R) is the correct explanation of (A).
(B) Both (A) and (R) are true, but (R) is not correct explanation of (A).
(C) (A) is true, but (R) is false.
(D) (A) is false, but (R) is true.
36. Assertion (A) : Brewster angle is the angle of incidence at which there is no reflection.
Reason (R) : For parallel polarisation, Brewster angle is given by following expression :
37. Assertion (A) : An EDFA is usually pumped at 980 nm wavelength, which means that Erbium ions at ground level absorb energy.
Reason (R) : This absorbed energy is transferred to high frequency signals to boost up.
38. Assertion (A) : D-flip-flops are used as buffer register.
Reason (R) : Flip-flops are free from “race-around” condition.
39. Assertion (A) : Routh Hurwitz criterion gives both absolute as well as relative stability using characteristic equation.
Reason (R) : For a system to be stable all roots of characteristic equation must lie in left half of s-plane.
40. Assertion (A) : Considering two p-n-p and n-p-n transistors of identical construction as far as shape, size and doping are concerned, the n-p-n transistor will have a better frequency response.
Reason (R) : The electron mobility is higher than that of the hole mobility.
41. Assertion (A) : If a semiconductor is placed in a transverse magnetic field B and an electric field E is applied across its other two faces, then it would produce an electric current ‘I’ in the direction perpendicular to both B and E.
Reason (R) : Hall coefficient is proportional to the mobility of the charge carriers in the semi conductor.
42. Assertion (A) : A monostable multivibrator can be used to alter the pulse width of a repetitive pulse train.
Reason (R) : Monostable multivibrator has a single stable state.
43. Assertion (A) : In a two port network, with 4 terminals four types of parameters like impedance, admittance, hybrid and transmission are considered and they are related to each other.
Reason (R) : The assumption made for the above statement is that there are no independent sources and non-zero initial conditions within the linear port network.
44. Assertion (A) : MOV A, 08 H It means the contents of memory address 08 H are moved to be contents of A.
Reason (R) : MV 1 A, 82 H It means that the contents of memory address 82 H are moved to be contents of A immediately.
45. Assertion (A) : To avoid repetition of code and bulky programs functionally related statements are isolated into a function.
Reason (R) : Function definition defines the body of the function.
Read the passage and answer the questions 46 to 50 that follows based on your understanding of passage :
An antenna is generally a metallic object, often a wire or collection of wires, used to convert high frequency current into electromagnetic waves and vice-versa. Antenna serve either or both of the following two functions, generation or the collection of electromagnetic energy. In a transmitting system, a radio-frequency signal is developed, amplified, modulated and applied to the antenna. The R-F currents flowing through the antenna produce electromagnetic waves which radiate into the atmosphere. In a receiving system, electromagnetic waves “cutting” through the antenna induce alternating currents for use by the receiver.
Efficient operation also requires that the receiving antenna be of the same polarization as the transmitting antenna. Polarization is the direction of the electric field and is therefore, the same as the antennas physical configuration. Thus vertical antenna will transmit vertical polarized light, any antenna having a physical length that is one-half wavelength of the applied frequency is called a Hertz antenna. Hertz antenna are predominantly used with frequencies above 2 MHz. Usually, at frequencies below 2 MHz, a Marconi type of antenna is used. The Marconi antenna is usually a quarter-wave grounded antenna or any odd multiple of a quarter wavelength.
The Yagi-Uda antenna consists of a drivers element and two or more parasitic elements. Yagi-Uda has two parasitic elements, a reflector and a director. This Yagi-Uda antenna provides about 7 dB of power gain with respect to a halfwavelength dipole reference. More complex antennas may be circularly polarized both vertically and horizontally polarized waves are radiated with equal power in both. If the powers are unequal the antenna is said to be elliptically polarized.
A horn is an ideal antenna for terminating a waveguide and may be conical, rectangular or sectorial. Wide band antennas either when the transmissions are wide band or when working of narrow channels over a wide frequency range is the major application. Helical antenna, which consists of a loosely wound helix backed u by a metal ground plane. Loop antennas are often used for direction finding. Loops have many shapes and generally consists of a single turn of wire. Discone is a ground plane antenna evolved from the vertical dipole and having a very similar radiation pattern.
46. A helical antenna is used for satellite tracking because of its
(A) circular polarization
(B) elliptical polarization
(C) broad band width
(D) good front-to-back ratio
47. The discone antenna is
(A) a useful direction finding antenna
(B) used as a radar receiving antenna
(C) circularly polarized like other circular antennas
(D) useful as a UHF receiving antenna
48. Which of the following antennas is best exerted from a waveguide ?
(A) Biconical
(B) Folded dipole
(C) Horn
(D) Discone
49. Which is a non-resonant antenna ?
(A) Marconi
(B) Rhombic
(C) Yagi-Uda
(D) Discone
50. An antenna is polarized in the plane of the field perpendicular to
(A) Electric field
(B) Magnetic field
(C) Both Electric and Magnetic field
(D) Field parallel to both electric and magnetic field
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