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UGC NET DEC 2012 : ELECTRONIC SCIENCE PAPER II

7 pages, 50 questions, 54 questions with responses, 95 total responses,

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PAPER-II ELECTRONIC SCIENCE Signature and Name of Invigilator 1. (Signature) __________________________ OMR Sheet No. : ............................................... (To be filled by the Candidate) (Name) ____________________________ 2. (Signature) __________________________ (Name) ____________________________ D 88 1 2 1 Time : 1 /4 hours] Number of Pages in this Booklet : 8 Instructions for the Candidates 1. Write your roll number in the space provided on the top of this page. 2. This paper consists of fifty multiple-choice type of questions. 3. 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 OMR Sheet Number should be entered on this Test Booklet. 4. Each item has four alternative responses marked (A), (B), (C) and (D). You have to darken the circle as indicated below on the correct response against each item. Example : where (C) is the correct response. 5. Your responses to the items are to be indicated in the OMR Sheet given inside the Paper I Booklet only. If you mark at any place other than in the circle in the OMR 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, Roll Number, Phone Number or put any mark on any part of the OMR Sheet, except for the space allotted for the relevant entries, which may disclose your identity, or use abusive language or employ any other unfair means, you will render yourself liable to disqualification. 9. You have to return the test question booklet and Original OMR Sheet to the invigilators at the end of the examination compulsorily and must not carry it with you outside the Examination Hall. You are, however, allowed to carry duplicate copy of OMR Sheet on conclusion of examination. 10. Use only Blue/Black Ball point pen. 11. Use of any calculator or log table etc., is prohibited. 12. There is no negative marks for incorrect answers. D-88-12 Roll No. (In figures as per admission card) Roll No.________________________________ (In words) [Maximum Marks : 100 Number of Questions in this Booklet : 50 1. 2. - 3. , - - , : (i) - - (ii) - / - - (iii) OMR - 4. (A), (B), (C) (D) : (C) 5. I OMR OMR , 6. 7. (Rough Work) 8. OMR , , , , , 9. - OMR OMR 10. / 11. ( ) 12. 1 P.T.O. ELECTRONIC SCIENCE Paper II Note : This paper contains fifty (50) objective type questions, each question carrying two (2) marks. Attempt all the questions. 1. For a JFET IDSS = 8 mA and peak voltage Vp = 8V, what will be the drain current for gate to source voltage of 2V ? (A) 4.5 mA (B) 8 mA (C) 16 mA (D) 12 mA 2. The leakage current in silicon p-n junction at room temperature is of the order of (A) mA (B) A (C) A (D) Amp 3. A tree in a network has a (A) closed path (B) no closed path (C) no nodes (D) no branches 4. A combinational circuit has inputs A, B and C and its K-map is as shown, the output of the circuit will be (A) (AB + AB) C (B) (AB + AB) C (C) A B C (D) A B C 8. The output f of the 4-to-1 Mux shown in the given figure is In the given network, Z11 is equal to 6 (A) 11 Ohm 4 (C) 11 Ohm 5. 7. (A) xy + x (C) x + y 6 (B) 11 Ohm 2 (D) 11 Ohm x+y (D) xy 9. Microprocessor 8086 allows floating point arithmetic calculations in (A) Maximum mode (B) Minimum mode (C) Both maximum and minimum modes (D) Neither in maximum nor in minimum mode 10. Which of the following chip is used in 8085 microprocessor 3-chip configuration ? (A) IC 8255 (B) IC 8155 (C) IC 8251 (D) IC 8257 Which is a three-terminal negative voltage regulator IC ? (A) 78 XX (B) IC 723 (C) LM 317 (D) 79 XX Three identical stages have overall upper 3 dB frequency of 2 KHz and lower 3 dB frequency of 20 Hz. What is the value of fH of each stage ? (A) 13 KHz (B) 26 KHz (C) 39 KHz (D) 52 KHz Paper-II (B) 6. 2 D-88-12 11. 12. 13. C Language is a _________ (A) High level language (B) Low level language (C) Machine level language (D) Middle level language 18. 19. The most suitable instrument for the measurement of voltage is (A) DVM (B) Analog voltmeter (C) CRO (D) DMM 20. In a C language expression, if the following expressions appear, which will be evaluated first ? (A) x + y (B) x y (C) (x + y) (D) x/y Dispersion shifted wave length is (A) 800 nm (B) 1550 nm (C) 1310 nm (D) 1200 nm The characteristic polynomial of a system is q(s) = 2s5 + s4 + 4s3 + 2s2 + 2s + 1 The system is (A) Stable (B) Marginally stable (C) Unstable (D) Oscillatory If E = 2 v/m of a wave in free space, the value of magnetic field (H) is 1 (A) A/m (B) 60 A/m 60 (C) 120 A/m (D) 240 A/m 14. The radiation resistance of a Hertizian dipole antenna of length 60 is (A) 0.493 Ohm (B) 0.22 Ohm (C) 2.2 Ohm (D) 22 Ohm 15. A 20 kW carrier is sinusoidally modulated by two carriers corresponding to modulation index of 30% and 40% respectively. The total radiated power is (A) 25 kW (B) 22.5 kW (C) 45.0 kW (D) 35.0 kW 16. ASCII code has 128 characters, which are binary coded. If a computer generates 106 characters per second, then minimum band width required to transmit this signal will be (A) 1.4 mbps (B) 14 mbps (C) 7 mbps (D) 0.7 mbps When the current through SCR is greater than holding current, then the voltage across the SCR is (A) 1.4 V (B) 0 V (C) Supply voltage (D) Half the load voltage D-88-12 Directions : Q. No(s) 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 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. 21. 17. 3 Assertion (A) : Tunnel diode provides oscillations in the microwave region. Reason (R) : The equivalent RC model of tunnel diode gives frequency in the microwave region. Paper-II 22. Assertion (A) : The roots of the denominator of a network function decide its stability. Reason (R) : The poles on real axis determine the damping factor of the system. 23. Assertion (A) : A parallel comparator ADC requires in built no. of comparators = 2N 1. Reason (R) : The speed of parallel comparator is limited by the speed of comparator. 25. Assertion (A) : Microcontrollers are preferred in Real time applications. Reason (R) : The on chip I/O integration has no bearing on the speed of microcontroller. 26. 29. Assertion (A) : The fast changing inputs do not depend upon slew rate property of an OPAMP. Reason (R) : Schmitt trigger does not work on the slew rate property of an OPAMP. 24. 28. Assertion (A) : In FORTRAN pointers are provided. Reason (R) : Pointers help to work with actual physical addresses. 27. 30. Consider the following four transistors : 1. CE mode 2. CC mode 3. MOSFET 4. FET The correct order in which, the input impedance increases is (A) 1, 2, 4, 3 (B) 1, 2, 3, 4 (C) 1, 3, 2, 4 (D) 4, 3, 2, 1 32. 4 Assertion (A) : The sign of all terms in the first row of Routh s array are checked, for stability considerations. Reason (R) : The number of sign changes equals the no. of roots on the right hand side of s-plane. 31. Assertion (A) : Divergence theorem is applicable for both static and time varying fields. Reason (R) : It is used to find enclosed charge from the knowledge of either D or E. Paper-II Assertion (A) : The back e.m.f. of a d.c. motor depends upon series winding and armature resistance. Reason (R) : When there is no load, the back emf is minimum. Assertion (A) : By using wavelength division, multiplexing the capacity of an optical fibre can be enhanced. Reason (R) : The separation between two adjacent channels in WDM is of the order of 50 nm. The correct order in which the power dissipation in transistor in power amplifiers decreases : 1. Class A 2. Class C 3. Class B 4. Class AB The correct order is (A) 1, 3, 2 and 4 (B) 1, 3, 4 and 2 (C) 1, 2, 3, 4 (D) 4, 3, 2, 1 D-88-12 33. 34. 35. The following are the interrupts of 8085 microprocessor : 1. INTR 2. TRAP 3. RST 7.5 4. RST 5.5 The correct order in which these interrupts will be executed, if arrive simultaneously : (A) 1, 2, 3, 4 (B) 2, 3, 1, 4 (C) 2, 3, 4, 1 (D) 4, 1, 2, 3 37. c. Laplace transform d. Z-transform Codes : a (A) iv (B) iv (C) iv (D) i 38. Following are the controllers : 1. On-off 2. PID 3. PI The correct order of the decrease in error output is (A) 1, 2, 3 (B) 1, 3, 2 (C) 3, 2, 1 (D) 3, 1, 2 a. b. c. d. Codes : a (A) i (B) ii (C) iv (D) iii D-88-12 b ii i i i c i ii iii iii 39. d iv iv iii iv 5 d ii i i iv List I a. Stability factor i. c. Lock range d. Negative feedback Codes : a b (A) ii iv (B) ii iii (C) iii iv (D) i ii List II i. base width modulation ii. AGC iii. 2 mV/ C iv. low power consumption c iii iii ii ii b iii iii ii ii b. Loop gain 1 Directions : Q. Nos. 36 to 45 : In the following questions, match List I and List II and select the correct answer using the codes given below the lists : List I P-N junction diode BJT FET MOSFET List II i. transient analysis ii. discrete time domain analysis iii. hybrid model iv. location of poles b. Y-parameters The following are the oscillators : 1. Crystal 2. Weinbridge 3. Colpitt s 4. Tunnel diode oscillator The correct sequence of decreasing order of the frequency of oscillation will be : (A) 4, 1, 3, 2 (B) 4, 1, 2, 3 (C) 4, 3, 2, 1 (D) 4, 2, 3, 1 36. List I a. Stability c iii iv ii iii List I a. Combinational logic b. Counters c. LIFO d. State diagram Codes : a b c (A) ii iii iv (B) ii iv iii (C) i ii iii (D) iv iii ii List II Large bandwidth ii. Voltage divider bias iii. Oscillators iv. PLL d i i i iv List II i. Sequential circuits ii. ROM iii. DVM iv. Shift register d i i iv i Paper-II 40. List I a. 8085 List II i. variable port addressing ii. serial communication iii. register bank iv. 2-key lockout b. 8086 c. 8279 d. 8051 Codes : a (A) i (B) iii (C) ii (D) ii 41. 42. b ii ii iv i List I a. while (1) c iii i i iv 43. d. Frequency modulation Codes : a b (A) iv i (B) iv ii (C) ii iii (D) iv iii d iv iv iii iii List II on-off control implementation b. paranthesis ii. infinite c. Switch-case iii. change of precedence d. If-then iv. multiple processing Codes : a b c d (A) i ii iii iv (B) iii iv ii i (C) ii iii iv i (D) ii iv iii i List I a. H d. J Codes : a (A) i (B) ii (C) ii (D) iv Paper-II 44. i. List II i. continuity equation ii. current density b. E c. D 45. iii. Faraday s law of induction iv. Gausses law b ii iii iii i c iii iv i ii List I a. QPSK b. Hamming code c. Superhetrodyne d iv i iv iii 6 List II i. deviation ii. I.F. iii. Error correction iv. 90 c ii iii iv ii List I a. relaxation oscillator b. S.M.P.S. c. population inversion d. bi-directional control Codes : a b c (A) iii i iv (B) iii ii i (C) iv i ii (D) iii i ii d iii i i i List II i. PWM ii. triac iii. UJT iv. Laser List I i. a. Strain measurement b. temperature ii. measurement c. Lissajous iii. figures d. E.M.G. iv. Codes : a b c (A) i ii iv (B) ii i iv (C) iii ii i (D) iii iv ii d ii iv iii iv List II Pt-100 load cell bio-medical signals C.R.O. d iii iii iv i D-88-12 46. For a d.c. output of 30 V, from a full wave rectifier, the PIV rating of the diode should be minimum (A) 50 V (B) 75 V (C) 100 V (D) 200 V 49. The critical inductance in mains power supply ensures that the current through L never becomes zero. For this, critical value of inductance is RL (A) 310 RL (B) 450 RL (C) 620 RL (D) 942 50. The output of such power supplies varies with variations in a.c. mains voltage, load current and temperature. In low voltage, low current model, IC 723 gives output voltage in the range of (A) 2 to 7 V (B) 5 to 10 V (C) 0 to 10 V (D) 0 to 7 V 48. Many instruments require dc power of their operation. This power is available from a portable cell, however, the power output is low besides other problems. AC power is continuously and easily available, so it is convenient to use it. However, ac power must be converted into dc power. The devices such as half-wave, full wave and bridge rectifiers convert bi-directional voltage to uni-directional voltage. However, the output has large ripple contents. Filters are used to reduce the ripple significantly. Various filters circuits and L, C, LC and CLC. The power supply with rectifier and filter is still unregulated. The minimum supply voltage to operate IC 7815 is (A) 15 V (B) 17 V (C) 25 V (D) 40 V 47. Read the passage below and answer the questions 46 to 50, that follows based on your understanding of the passage : In series pass voltage regulator using zener diode, the function of zener diode is a (A) Voltage regulator (B) Voltage comparator (C) Breakdown diode (D) Temperature compensator In order to maintain the output at constant level, voltage or current regulation is necessary. This is obtained by using series or shunt feedback. In addition to regulation, the power supply also requires protection e.g. overload, over current or short circuit protection. Pre- regulation is also carried out to improve the stability. Regulators can be designed by using discrete components. However, IC regulators are also available. These regulators have facilities like : (i) voltage / current boosting (ii) thermal shut-down (iii) floating point to facilitate higher output voltage. (iv) switching regulator to reduce the power dissipation. D-88-12 7 Paper-II Space For Rough Work Paper-II 8 D-88-12

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