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UGC NET JUN 2008 : ELECTRONIC SCIENCE PAPER II

16 pages, 50 questions, 50 questions with responses, 72 total responses,

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Signature and Name of Invigilator OMR Sheet No. : ...................................................... (To be filled by the Candidate) 1. (Signature) Roll No. (Name) (In figures as per admission card) Roll No. 2. (Signature) (In words) (Name) Test Booklet No. J 8 8 0 8 PAPER II ELECTRONIC SCIENCE Time : 1 hours] Number of Pages in this Booklet : 16 Number of Questions in this Booklet : 50 U Instructions for the Candidates 1. 2. 3. 4. 1. U DU U S U U U U Write your roll number in the space provided on the top of this page. This paper consists of fifty multiple-choice type of questions. At the commencement of examination, the question booklet will be given to you. In the first 5 minutes, you are requested to open the booklet and compulsorily examine it as below : (i) To have access to the Question Booklet, tear off the paper seal on the edge of this cover page. Do not accept a booklet without sticker-seal and do not accept an open booklet. (ii) Tally the number of pages and number of questions in the booklet with the information printed on the cover page. Faulty booklets due to pages/questions missing or duplicate or not in serial order or any other discrepancy should be got replaced immediately by a correct booklet from the invigilator within the period of 5 minutes. Afterwards, neither the question booklet will be replaced nor any extra time will be given. (iii) After this verification is over, the Test Booklet Number should be entered in the OMR Sheet and the OMR Sheet Number should be entered on this Test Booklet. Each item has four alternative responses marked (A), (B), (C) and (D). You have to darken the oval as indicated below on the correct response against each item. Example : A B C 2. - 3. U U U, - S U U U - S U (i) - S U U U U S U U- U S S U U (ii) U DU U U U - S DU U U U U U U S DU / U U U U U S S U U U U U S U U - S U U - S U UQ (iii) - S R OMR U U U U OMR R - S U U 4. U U (A), (B), (C) (D) U U U U U D A B C D (C) U 5. U U I U U- U where (C) is the correct response. 5. Your responses to the items are to be indicated in the Answer Sheet given inside the Paper I booklet only . If you mark at any place other than in the ovals in the Answer Sheet, it will not be evaluated. 6. Read instructions given inside carefully. 7. Rough Work is to be done in the end of this booklet. 8. If you write your name or put any mark on any part of the test booklet, except for the space allotted for the relevant entries, which may disclose your identity, you will render yourself liable to disqualification. 9. You have to return the test question booklet to the invigilators at the end of the examination compulsorily and must not carry it with you outside the Examination Hall. 10. Use only Blue/Black Ball point pen. 11. Use of any calculator or log table etc., is prohibited. 12. There is NO negative marking. J 8808 [Maximum Marks : 100 U U U S U U U , U 6. U U 7. (Rough Work) S DU U U 8. U- S U , U U U U 9. U # U U- S U U U U U # U U U / U Z U S U 11. U ( U U) U U 12. U U 10. 1 P.T.O. ELECTRONIC SCIENCE PAPER II Note : 1. This paper contains fifty (50) objective-type questions, each questions carrying two (2) marks. Attempt all of them. What is the type of capacitance effect exhibited by the PN junction, when it is reversed biased ? (A) (B) Diffusion capacitance (C) 2. Transition capacitance Space charge capacitance (D) Drift capacitance Recombination of electrons and holes takes place when : (A) (B) A positive ion and a negative ion bond together (C) Avalanche electron becomes a conduction electron (D) 3. An electron from conduction band falls into a hole in valence band An atom is formed XL is : (A) (B) directly related to inductance (C) directly related to both frequency and induction (D) 4. directly related to frequency none of the above In a purely inductive circuit : (A) (C) 5. voltage lags current by 908 (B) voltage and current are in phase (D) current lags voltage by 908 voltage and current are not in phase The PPM can be converted into PDM by modifying the circuit of : (A) Monostable multivibrator (B) Astable multivibrator (C) Bistable multivibrator (D) All the above J 8808 2 6. CMRR (Common Mode Rejection Ratio) for a differential amplifier should be : (A) 7. Zero (B) Unity (C) Small Large A toggle operation is used : (A) with a gate circuit (B) with a flip-flop (C) 8. (D) without a flip-flop (D) none of the above In a bistable multivibrator, commutating capacitors are used to : (A) provide ac coupling (C) 9. increase the base storage charge (B) increase the speed of response alter the frequency of the output (D) In 8085 microprocessor, the value of the most significant bit of the result following the execution of any arithmetic of Boolean instruction is stored in the : (A) (B) auxiliary carry status flag (C) 10. carry status flag sign status flag (D) zero status flag The interface chip is used for data transmission between 8086 and a 16 - bit ADC is : (A) 11. 8259 (B) 8255 (C) 8253 (D) 8251 Consider the following statements : (i) An assembly language program runs faster than a high level language program to produce the desired result. (ii) An assembler which runs on a computer for which it produces object codes is called a resident assembler. (iii) A cross-assembler is an assembler that runs on a computer other than that for which it produces machine codes. (iv) A one-pass assembler reads the assembly language programs only once. Which of these statements are correct ? (A) (i), (ii) and (iii) (B) (ii), (iii) and (iv) (C) (i) and (iv) (D) (i), (ii), (iii) and (iv) J 8808 3 P.T.O. 12. An interrupt in which the external device supplies its address as well as the interrupt request, is known as : (A) (B) Maskable interrupt (C) 13. Vectored interrupt Polled interrupt (D) Non-maskable interrupt Modulation is a process of : (A) (B) improving thermal stability (C) combining audio and radio frequency waves at the transmitter (D) 14. reducing distortion generating constant frequency waves Transmission of signals in a terrestrial microwave system is achieved through : (A) (B) line-of-sight mode (C) 15. reflection from the ionosphere reflection from the ground (D) diffraction from the stratosphere Consider the following statements : (i) The derivative control improves the overshoots of a given system. (ii) The derivative control reduces steady-state error. (iii) Integral control reduced steady-state error. (iv) Integral control does not affect stability. Of these statements : (A) (i) and (iii) are correct (B) (i) and (ii) are correct (C) (ii) and (iv) are correct (D) (ii) and (iii) are correct J 8808 4 16. For a given data rate, the bandwidth required with m-ary transmission is smaller than that for binary transmission by : (A) 17. log 2m (B) log 2 m m (C) 2 log 2 m (D) log 2 m 2 A relaxation oscillator is one which : (A) (B) has two stable states (C) 18. oscillates continuously relax indefinitely (D) produces non-sinusoidal output When a plane wave propagating through free space, the direction of the field : (i) E is perpendicular to the direction of propagation (ii) H is perpendicular to the direction of propagation (iii) E is perpendicular to the direction of the field H Codes : (A) (B) (ii) and (iii) (C) 19. (i) and (ii) (i) and (iii) (D) (i), (ii) and (iii) Which one of the following is capable of giving the highest data speed ? (A) (B) Microwave LOS link (C) 20. Coaxial cable link Microwave satellite system (D) Optical fiber system Quantizing noise occurs in : (A) Time-division multiplexing (B) Frequency-division multiplexing (C) Pulse-code modulation (D) Pulse-width modulation J 8808 5 P.T.O. (Questions 21 to 30) : The following items consist 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 the Reason (R) are individually true and if so, whether the Reason is a correct explanation of the Assertion. Select your answers to these items using codes given below and mark your answer accordingly. Codes : (A) (B) Both (A) and (R) are true but (R) is not the correct explanation of (A) (C) (A) is true but (R) is false (D) 21. Both (A) and (R) are true and (R) is the correct explanation of (A) (A) is false but (R) is true Assertion (A) : Superposition theorem can be used to determine the output of a fullwave rectifier whose inputs are sinusoidal signal sources of different frequencies connected in series. Superposition theorem holds good for all linear systems. Assertion (A) : R - 2R ladder type D/A converter has a higher speed of conversion than a weighted resistance D/A converter. Reason (R) : R - 2R ladder type D/A converter uses a smaller number of components than the weighted resistance D/A converter. Assertion (A) : The do-while statement is used less frequently than the while statement. Reason (R) : 24. At room temperature, the p-type semiconductor is rich in holes whereas the n-type semiconductor is rich in electronics. Reason (R) : 23. At room temperature, the Fermi level in a p-type semiconductor lies nearer to the valence band, whereas that in the n-type semiconductor lies nearer to the conduction band. Reason (R) : 22. Assertion (A) : For most applications, it is more natural to test for continuation of a loop at the beginning rather than at the end of the loop. J 8808 6 25. Thyristors provide controlled rectification and also the power loss in them is less compared to that in power diodes. Assertion (A) : Stimulated emission is the key to the operation of LASER. An important property of laser radiation is its coherence, under which is meant the corelation between the phases of oscillation at different positions in space and at various moments of time. Assertion (A) : A half-adder is faster than full-adder. A half adder gives only one output while a full adder gives two outputs. Assertion (A) : Optical fibers have broader bandwidth to conventional copper cables. Reason (R) : The information carrying capacity of optical fibers is limited by Rayleigh scattering loss. 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) : 30. Thyristors are preferred to power diodes in variable power rectifiers. Reason (R) : 29. Assertion (A) : Reason (R) : 28. Unit step function is the most common input found in practice. Reason (R) : 27. The transient performance of a feedback control system is normally analyzed by using a unit-step function as the reference input. Reason (R) : 26. Assertion (A) : Hall coefficient is proportional to the mobility of charge carriers in the semiconductor. J 8808 7 P.T.O. 31. Consider the following steps : (i) Etching (ii) Exposure to UV radiation (iii) Stripping (iv) Developing After a wafer has been coated with photoresist, the correct sequence of these steps in photolithography is : Codes : (A) (B) (ii), (iv), (i), (iii) (C) 32. (ii), (iv), (iii), (i) (iv), (ii), (i), (iii) (D) (iii), (ii), (iv), (i) The Microprocessor chips available with different speed are : (i) 8085 (ii) 80286 (iii) 8086 (iv) 80486 Codes : (A) (B) (i), (iii), (ii), (iv) (C) 33. (i), (ii), (iii), (iv) (ii), (iv), (i), (iii) (D) (iv), (i), (iii), (ii) Each instruction in an assembly program has the following field : (i) Label field (ii) Mnemonic field (iii) Operand field (iv) Comment field The correct sequence/order of these field is : (A) (i), (ii), (iii), (iv) (B) (i), (ii), (iv), (iii) (C) (ii), (i), (iii), (iv) (D) (ii), (i), (iv), (iii) J 8808 8 34. Consider the Analog to Digital converters given below : (i) Successive approximation ADC (ii) Dual-slope ADC (iii) Counter method ADC (iv) Simultaneous ADC The correct sequence of the ascending order in terms of speed of the above ADC s is : (A) (B) (ii), (i), (iii), (iv) (C) 35. (i), (ii), (iv), (iii) (iv), (ii), (i), (iii) (D) (iii), (ii), (i), (iv) Consider the following devices : (i) BJT in CB mode (ii) BJT in CE mode (iii) JFET (iv) MOSFET The correct sequence of these devices in increasing order of their input impedance is : (A) (B) (ii), (i), (iii), (iv) (C) 36. (i), (ii), (iii), (iv) (ii), (i), (iv), (iii) (D) (i), (iii), (ii), (iv) Match List-I with List-II and select the correct answer using the codes given below the list : List-I List-II (a) LVDT (i) Pressure (b) Bourdon gauge (ii) Temperature (c) Strain gauge (iii) Displacement (d) Thermistor (iv) Stress Codes : (a) (b) (c) (d) (A) (iv) (iii) (ii) (i) (B) (iii) (ii) (i) (iv) (C) (iv) (i) (iii) (ii) (D) (iii) (i) (iv) (ii) J 8808 9 P.T.O. 37. Match List-I with List-II : List-I List-II (a) Flip-Flop can be used as latch (i) D-Flip-Flop (b) Flip-Flop can be used as delayed (ii) Master-slave (c) Flip-Flop does not have race problem (iii) JK (d) Flip-Flop can be used as shift registers (iv) RS Codes : (a) (c) (d) (A) (iv) (i) (ii) (iii) (B) (ii) (iv) (i) (iii) (C) (i) (iii) (ii) (iv) (D) 38. (b) (iii) (i) (iv) (ii) Match List-I with List-II : List-I List-II (a) BJT (i) Pinch off effect (b) FET (ii) Controlled rectification (c) SCR (iii) Negative resistance characteristics (d) Tunnel diode (iv) Punch through effect Codes : (a) (b) (c) (d) (A) (iv) (iii) (ii) (i) (B) (iii) (ii) (i) (iv) (C) (iv) (i) (ii) (iii) (D) (iii) (i) (iv) (ii) J 8808 10 39. Match List-I with List-II : List-I List-II (a) SID, SOD (i) Wait state (b) READY (ii) Interrupt (c) TRAP (iii) Serial data transfer (d) ALE (iv) Address latch control Codes : (a) (c) (d) (A) (iii) (i) (iv) (ii) (B) (iii) (i) (ii) (iv) (C) (iv) (iii) (ii) (i) (D) 40. (b) (iv) (iii) (i) (ii) Match List-I with List-II : List-I List-II (a) Parallel comparator (i) Null balancing type (b) Successive approximation (ii) Fastest converter (c) Dual slope (iii) Voltage dependent conversion type (d) Counter type (iv) Integrating type Codes : (a) (b) (c) (d) (A) (ii) (i) (iii) (iv) (B) (ii) (i) (iv) (iii) (C) (i) (ii) (iv) (iii) (D) (i) (ii) (iii) (iv) J 8808 11 P.T.O. 41. Match List-I with List-II : List-I List-II (a) Frequency modulation (i) Envelop detection (b) Double sideband suppressed singal carrier (ii) Companding (c) PCM (iii) Balance modulator (d) Amplitude modulation (iv) Pre-emphasis and de-emphasis Codes : (a) (c) (d) (A) (i) (ii) (iii) (iv) (B) (i) (ii) (iv) (iii) (C) (iv) (iii) (i) (ii) (D) 42. (b) (iv) (iii) (ii) (i) Match List-I with List-II : List-I List-II (a) Solar cell (i) Delivers power to a load (b) LASER (ii) Spontaneous emission (c) Photodiode (iii) Detects light incident upon it (d) LED (iv) Stimulated emission Codes : (a) (b) (c) (d) (A) (iv) (ii) (i) (iii) (B) (ii) (i) (iv) (iii) (C) (i) (iv) (iii) (ii) (D) (ii) (iii) (i) (iv) J 8808 12 43. Match List-I with List-II : List-I List-II (a) 8086 (i) 8-bit processor (b) 8085 (ii) Interface chip (c) 8255 (iii) 16-bit processor (d) 80486 (iv) 64-bit processor Codes : (a) (c) (d) (A) (iii) (i) (ii) (iv) (B) (i) (ii) (iii) (iv) (C) (iv) (i) (ii) (iii) (D) 44. (b) (ii) (i) (iv) (iii) Match List-I with List-II : List-I List-II (a) Monostable multivibrator (i) no-stable state (b) Astable multivibrator (ii) one-stable state (c) Free-running multivibrator (iii) two-stable state (d) Bi-stable multivibrator (iv) alternate high and low output Codes : (a) (b) (c) (d) (A) (i) (ii) (iii) (iv) (B) (ii) (i) (iv) (iii) (C) (i) (iii) (ii) (iv) (D) (iii) (iv) (ii) (i) J 8808 13 P.T.O. 45. Match List-I with List-II : List-I List-II (a) Single mode optical fiber (i) data rate is lowest (b) Multi-mode optical fiber (ii) data rate is highest (c) Graded index optical fiber (iii) data rate is medium (d) Simple glass rod fiber (iv) data transfer not possible Codes : (a) (b) (c) (d) (A) (i) (ii) (iii) (iv) (B) (iii) (ii) (i) (iv) (C) (iv) (i) (ii) (iii) (D) (ii) (i) (iii) (iv) Read the passage and answer the questions that follow based on your understanding of the passage : Like a transmission line, an antenna is a device with distributed constants, so that current, voltage and impedance all vary from one point to the next one along it. This factor must be taken into account when considering important antenna properties are expressed in terms of those of comparison antennas. Useful comparison antenna is the elementary doublet. This is defined as a piece of infinitely thin wire with a length that is negligible compared to the wavelength of signal being radiated, and having constant current along it. Long thin wires which are often used in practice. This may be resonant which effectively means that their length is multiple of half-wavelength of the signal or non-resonant in which case the reflected wave have been suppressed. The resonant antennas are bidirectional but non-resonant antennas are unidirectional since there is no reflected waves. Simple antennas are horizontally on vertically polarized. More complex antennas are may be circularly polarized. The Yagi-uda antenna employs a folded dipole and parasitic element to obtain reasonable gain the HF and VHF ranges. The rhombic antenna is a non-resonant antenna providing excellent gain in HF range. High gain and narrow bandwidth are special requirement of microwave antennas. The microwave antennas are horn and lenses. A horn is an ideal antenna for terminating a waveguide and may be conical or rectangular. Wideband antennas are required in transmission of narrow channels over a wide frequency range. The folded dipole (hence Yagi-uda antenna) and the rhombic all have good broad band properties - Helical antenna is circularly polarized and hence ideal for transionospheric communication. When multiactive bandwidths are required, the antennas used often have constant angle feature. One such antenna is discone. Which is low gain multiactive and normally used in ultrahigh frequency range. 46. Which one of the following consists of non-resonant antennas ? (A) The rhombic antenna (B) The folded dipole (C) The end-fire array (D) The broad side array J 8808 14 47. An antenna that is circularly polarized is the : (A) (B) small circular loop (C) 48. helical parabolic reflector (D) yagi-uda Which one of the following terms does not apply to the Yagi-uda array ? (A) (B) parasitic element (C) 49. good band width folded dipole (D) high gain One of the following is very useful as a multiband UHF receiving antenna. This is : (A) (B) Folded dipole (C) 50. Discone antenna Log periodic (D) Square loop Which of the following antennas is best excited from a wave-guide ? (A) Biconical (B) Horn (C) Helical (D) Discone -oOo- J 8808 15 P.T.O. Space For Rough Work J 8808 16

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Additional Info : Ugc Net June 2008 Question Paper - Electronic Science Paper II
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