india’s no 1 ies-2010 ies academy et (paper-i) paper i ies 2010.pdfindia’s no 1 ies-2010 ies...

India’s No 1 IES-2010

IES Academy ET (Paper-I)

www.iesacademy.com Email: [email protected] Page-1 __

25, 1st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

Electronics Engineering (Paper-I) Time Allowed: Two Hours Maximum Marks: 200

INSTRUCTIONS

1. IMMEDIATELY AFTER THE COMMENCEMENT OF THE EXAMINATION, YOU SHOULD CHECK THAT THIS TEST BOOKLET DOES NOT HAVE ANY UNPRNTED OR TORN OR MISSING PAGES OR ITEMS, ETC. IF SO, GET IT REPLACED BY A COMPLETE TEST BOOKLET

2. ENCODE CLEARLY THE TEST BOOKLET SERIES A, B, C OR D AS THE CASE MAY BE IN THE APPROPRIATE PLACE TN THE ANSWER SHEET.

3. You have to enter your Roll Number on the Test Booklet in the Box provided alongside. DO NOT write anything else on the Test Booklet.

4. This is Test Booklet contains 120 items (questions). Each item comprises four responses (answers). You will select the response which you want to mark on the Answer Sheet. In case you feel that there is more than one correct response, mark the response which you consider the best. In any case, choose ONLY ONE response for each item.

5. You have to mark all your responses ONLY on the separate Answer Sheet provided. See directions in the Answer Sheet.

6. All items carry equal marks.

7. Before you proceed to mark in the Answer Sheet the response to various items in the Test Booklet, you have to fill in some particulars in the Answer Sheet as per instructions sent to you with your Admission Certificate.

8. After you have completed filling in all your responses on the Answer Sheet and the examination has concluded, you should hand over to the Invigilator only the Answer Sheet. You are permitted to take away with you the Test Booklet.

9. Sheets for rough work are appended in the Test Booklet at the end.

10. Penalty for wrong answers: THERE WILL BE PENALTY FOR WRONG ANSWERS MARKED BY A CANDIDATE IN THE OBJECTIVE TYPE QUESTION PAPERS. (i) There are four alternatives for the answer to every question. For each question

for which a wrong answer has been given by the candidate, one-third (0.33) of the marks assigned to that question will be deducted as penalty.

(ii) If a candidate gives more than one answer, it will be treated as a wrong answer even if one of the given answers happens to be correct and there will be same penalty as above to that question.

(iii) If a question is left blank, i.e., no answer is given by the candidate, there, will be no penalty for that question.

DO NOT OPEN THIS TEST BOOKLET UNTIL YOU ARE ASKED TO DO





Q1. A causal stable LTI system S has the frequency response ( ) 2jH jw

6 5jω + 4

=− ω + ω

What is the output of S when the input is ( ) ( ) ( )4t 4tx t e u t te u t ?− −= −

( ) ( ) ( ) ( ) ( ) ( )( ) ( ) ( ) ( ) ( ) ( )

2t 4t 2t 4t

2t 4t 4t 4t

a 0.5e 0.5e u t b e 0.5e u t

c 0.5e e u t d 0.5e e u t

− − − −

− − − −

− −

− −

Q2. Consider an LTI system whose response to the input

( ) ( ) ( ) ( )t 3t t 4tx t e e u t is y t 2e 2e u t .− − − −⎡ ⎤ ⎡ ⎤= + = −⎣ ⎦ ⎣ ⎦ Find the frequency response of this system.

( ) ( ) ( ) ( ) ( ) ( )

( ) ( ) ( ) ( ) ( ) ( )

1 3 3 3a b4 j 2 j 2 4 j 2 2 j

3 3 1 3c d4 j 2 2 j 4 j 2 2 j

+ ++ ω + ω + ω + ω

+ ++ ω + ω + ω + ω

Q3. The procedure for interpolation or up sampling by an integer factor N can

be thought of as the cascade of two operations. The first operation, involving system A, corresponds to inserting N-1 zero-sequence values between each sequence value of x[n], so that

dp

nx , n 0, N, 2N, ...x n Notherwise

0,

⎧ ⎡ ⎤= ± ±⎪ ⎢ ⎥=⎡ ⎤ ⎨ ⎣ ⎦⎣ ⎦

⎪⎩

For exact band – limited interpolation, ( )jH e ω is an ideal lowpass filter. Determine whether or not system A is:

(a) Linear (b) Non linear (c) Linear at some points, otherwise non-linear (d) Can’t say Q4. A signal x(t) with Fourier transform X(jω) undergoes impulse – train

sampling to generate

( ) ( ) ( )pn

4

x t x nT t nT

where T 10

∞

= −∞

−

= δ −

=

∑

If ( )X j 0 for 5000ω = ω > π does the sampling theorem guarantee that x(t) can be recovered exactly from ( )px t ?

(a) Yes (b) No (c) Some part of signal can be recovered exactly (d) Data insufficient. Q5. The following is known about a discrete – time LTI system with input x[n]

and output y[n]: (1) If x[n] = ( )n2− for all n, then y[n] = 0 for all n.





(2) If x[n] = ( )n1 U n

2⎛ ⎞⎜ ⎟⎝ ⎠

for all n, then y[n] for all n is of the form

n1y[n] n a u[n]4

⎛ ⎞= δ +⎡ ⎤⎣ ⎦ ⎜ ⎟⎝ ⎠

where a is a constant.

Determine the value of the constant a.

( ) ( ) ( ) ( )1 3 7a b c d None of them8 8 8

Q6. The autocorrelation function of a sinusoid cos (wt) is given by (a) cos(wt) (b) 2 cos(wt) (c) 1/2 cos(wt) (d) none Q7. The energy of the signal 2e-t/2u(t) is given by (a) 2 (b) Infinite (c) 3 (d) 4 Q8. A random process is called ergodic if (a) It is ergodic in mean (b) It is ergodic in autocorrelation (c) It is ergodic in mean & autocorrelation (d) None Q9. If x(t) has fundamental period T, x(3t – 1) has fundamental period of …..? (a) T (b) T/2 (c) T/3 (d) Can’t be determined Q10. We are given the following 5 facts about a discrete time singnal x[n] with Z –

transform X(z): (a) x[n] is real and right sided. (b) X(z) has exactly 2 poles. (c) X(z) has 2 zeroes at the origin.

(d) X(z) has a pole at j31z e

2

π

=

(e) X(1) = 83

Determine X(z)

( ) ( ) ( ) ( )2 2 2 2

2 2 2 2

Z 2Z 2Z Za b c dZ 1 Z 1 Z 1 Z 1Z Z Z Z4 2 4 2 2 4 2 4

− + − + − + − +

Q11. Determine the z-transform for n 11 u n 3

2

+⎛ ⎞ +⎡ ⎤⎣ ⎦⎜ ⎟⎝ ⎠

( ) ( ) ( ) ( )3 3 3 3

1 1 1 12z 4z 6z 8za b c d

8 z 8 z 2 z 2 z− − − −− − − −

Q12. Indicate the region of convergence of Z-transform of n 21 u n 2

3

−⎛ ⎞ −⎡ ⎤⎣ ⎦⎜ ⎟⎝ ⎠





( ) ( ) ( ) ( )1 1 1a 0 z b z c z 1 d z 14 4 4

< < < < < >

Q13. A pressure gauge that can be modeled as an LTI system has a time response

to a unit step input given by t t(1 e te )u(t)− −− − . For the certain input x(t), the output is observed to be ( )t 3t2 3e e u(t).− −− + For this observed measurement, determine the true pressure input to the gauge as a function of time.

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )3t 3t 3t t 3t ta 2e 4 u(t) b 4e 2 u(t) c 2e 4e u(t) d 4e 2e u(t)− − − −+ + + + Q14. The signal y(t) is obtained by convolving signals ( ) ( )1 2x t and x t where:

( )( )

1

2

X 0 for 1000 &

X 0 for 2000

ω = ω > π

ω = ω > π

Impulse train sampling is performed on y(t) to get ( ) ( ) ( )py t y nT t nT∞

−∞

= δ −∑ .

Specify the range of values of T so that y(t) may be recovered from yp(t). ( ) ( ) ( ) ( )3 2a T 1 sec b T 0.5 sec c T 10 sec d T 10 sec− −< < < < Q15. Metal when compared to non-metals (a) Are less electronegative & have smaller atomic radii. (b) Have greater ionization energies & smaller atomic radii. (c) Are less electronegative & have larger atomic radii. (d) Have less ionization energies & smaller atomic radii. Q16. A semiconductor strain gauge has the advantage over the normal strain

gauge that (a) It is more linear (b) It has excellent hysteresis characteristics (c) Its low cost (d) All the above Q17. The gauge factor of strain gauge is 2, stress is 1050 kg/cm2, Y = 2.1 × 106 kg/

cm2 and change in resistance is 1Ω. Find the value of resistance. (a) 2000Ω (b) 1500Ω (c) 1000Ω (d) 2500Ω Q18. Which one of the following is used for the measurement of loss angle in a

dielectric? (a) Schering bridge (b) Megger (c) Spectrum Analyser (d) None Q19. A capacitive transducer has two plates of area 5 cm2 each separated by an

air gap. The displacement sensitivity due to air gap is 11.06 pF/cm. Find the air gap.

(a) 2mm (b) 4 mm (c) 4.5 mm (d) 5.1 mm Q20. A Hall-effect transducer with Hall-coefficient, K = -1 × 10-8 is required to

measure a magnetic field of 10,000 gauss. A 2 mm bismuth slab is used as the transducer with a current I. The output voltage of the transducer is

51.5 10 V.−× Find I. (a) 1A (b) 2A (c) 2.7 A (d) 3A





Q21. A linear discrete – time system has the characteristic equation,

3Z 0.64z 0.− = The system is (a) Stable (b) Marginally (c) unstable (d) can’t be determined Q22. Match List – I (Materials) with List – II (Applications of materials) & select

the correct answer given below: List – I List - II (A) AL2O3 (1) LASER (B) Ruby (2) HIGH VALUE CAPACITOR (C) BaTiO3 (3) FERRIMAGNETIC (D) YIG (4) INSULATOR Codes: A B C D A B C D (a) 4 1 2 3 (b) 4 2 1 3 (c) 1 4 2 3 (d) 1 4 3 2 Q23. A 0 to 200V dc moving coil voltmeter has a guaranteed accuracy of 0.5% of

full – scale reading. The voltage measured by instrument is 100 V. What is the limiting error?

(a) 0.5% (b) 1% (c) 1.5% (d) 2.5% Q24. A variable reluctance type tachometer has 135 teeth on the rotor. The

counter records 27,000 pulses per second. The rotational speed is: (a) 3000 rpm (b) 12,000 rpm (c) 17,000 rpm (d) None Q25. Assertion (A): Isotopes have different atomic no.s and the same atomic

masses. Reason (R): The difference in composition between isotopes is in the no. of

neutrons in the nucleus. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q26. Assertion (A): In two wattmeter method, when the readings of the two watt-

meters are equal but of opposite sign, p.f is zero. Reason (R): Two – watt meter method, is used only for star – connected

three – phase circuits. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q27. Assertion (A): In an electromagnetic flow meter, a non – magnetic & non –

conducting pipe is used for measuring the flow of fluid of low conductivity. Reason (R): The meter calibration is un-affected as the viscosity of the fluid

changes. (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 the correct explanation of A





(c) A is true but R is false (d) A is false but R is true Q28. Assertion (A): Capacitive transducers have a good frequency response &

show non – linear behavior. Reason (R): Capacitive transducers show edge effects. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q29. Assertion (A): A step function voltage is applied to an RLC series circuit

having R = 2Ω, L = 1H & C = 1F. Reason (R): The transient current response of the circuit is critically

damped. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q30. Assertion (A): Moving iron instrument has an unpolarised meter with two

iron vanes. Reason (R): Iron vane placed in the magnetic field gets magnetized in the

direction of current through electromagnet. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q31. Assertion (A): Potentiometer method of dc voltage measurement is accurate. Reason (R): Potentiometer method uses zero centre galvanometer. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q32. Assertion (A): A dual trace oscilloscope offers two modes, chop & alternate. Reason (R): Alternate mode can be used for displaying two waveforms of

one low frequency & other high frequency. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q33. Assertion (A): The conductivity of Ge is higher than that of Si. Reason (R): Mobility of charge carriers is better in Ge. (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true





Q34. Assertion (A): For high ‘Q’ circuits, the poles of Y(s) must lie close to the w-

axis in the complex frequency plane. Reason (R): Q is inversely proportional to damping factor ξ . (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 the correct explanation of A (c) A is true but R is false (d) A is false but R is true Q35. The v-i characteristics as seen from the terminal – pair (A, B) of the network

of Figure (a) is shown in Figure (b). If an inductance of value 6 mH is connected across the terminal – pair (A, B), the time constant of the system will be

(a) 3 μsec (b) 12 sec (c) 32 sec (d) Unknown, unless the actual network is specified

Q36. The unit impulse response of a system is given as c(t) = - 4e-t + 6 e-2t. The step

response of the same system for t ≥ 0 is equal to

( ) ( )( ) ( )

2t t 2t t

2t t 2t t

a 3e 4e 1 b 3e 4e 1c 3e 4e 1 d 3e 4e 1

− − − −

− − − −

− + + − + −

− − − + −

Q37. A coil (which can be modeled as a series – RL circuit) has been designed for

high Q performance at a rated voltage and a specified frequency. If the frequency of operation is doubled, and the coil is operated at the same rated voltage, then the Q-factor and the active power P consumed by the coil will be affected as follows:

(a) P is doubled, Q is halved (b) P is halved, Q is doubled (c) P remains constant, Q is doubled (d) P decreases 4 times, Q is doubled Q38. An ideal voltage source will charge an ideal capacitor (a) In infinite time (b) Exponentially (c) Instantaneously (d) None of the above Q39. Energy stored in a capacitor over a cycle, when excited by an a.c. source is (a) The same as that due to a d.c. source of equivalent magnitude (b) Half of that due to a d.c source of equivalent magnitude (c) Zero (d) None of the above





Q40. For the circuit shown in Figure, the Norton equivalent source current value

is ............ and its resistance is............ (a) 2 A, 4.5 Ω (b) 4.5 A, 2 Ω (c) 2 A, 4 Ω (d) 4 A, 2 Ω

Q41. A 10 V battery with an internal resistance of 1 Ω is connected across a non-

linear load whose V - I characteristic is given by 7I = V2 + 2V. The current delivered by the battery is ………… A.

(a) 24 (b) 5 (c) 24.5 (d) 5.24 Q42. The voltage and current waveforms for an element are shown in Figure.

The circuit element is ……… and its value is ……….

(a) Inductor, 2H (b) Capacitor, 2F (c) Both inductor (2H) and capacitor (2F) (d) None Q43. Consider a DC voltage source connected to a series R-C circuit. When the

steady-state reaches, the ratio of the energy stored in the capacitor to the total energy supplied by the voltage source, is equal to

(a) 0.362 (b) 0.500 (c) 0.632 (d) 1.000 Q44. Two 2 H inductance coils are connected in series and are also magnetically

coupled to each other-the coefficient of coupling being 0.1. The total inductance of the combination can be

(a) 0.4 H (b) 3.2 H (c) 4.0 H (d) 4.4 H Q45. The RMS value of a rectangular wave of period T, having a value of + V for a

duration, T1 (<T) and - V for the duration, T – T1 = T2, equals

(a) V (b) 1 2T T VT− (c) V

2 (d) 1

2

T VT

Q46. The inverse Laplace transform of the function ( )( )

s 5s 1 s 3

++ +

is

( ) ( ) ( ) ( )t 3t t 3t t 3t t 3ta 2e e b 2e e c e 2e d e 2e− − − − − − − −− + − + Q47. The voltage C1 C2 C3V , V and V across the capacitors in the circuit in Figure

under steady state, are respectively (a) 80 V, 32 V, 48 V (b) 80 V, 48 V, 32 V (c) 20 V, 8 V, 12 V (d) 20 V, 12 V, 8 V





Q48. In the circuit shown in Figures (a) - (c), assuming initial voltages across

capacitors and currents through the inductors to be zero, at the time of switching (t = 0), then at any time t > 0, match List-I & List-II

(1) Current increases monotonically with time

(2) Current decreases monotonically with time

(3) Current remains constant at V/R

(4) Current first increases, then

decreases (5) No current can ever flow

(a) (A) – (1) (B) – (2) (C) – (4) (b) (A) – (2) (B) – (3) (C) – (4) (c) (A) – (1) (B) – (3) (C) – (4) (d) (A) – (3) (B) – (2) (C) – (1) Q49. The current i4 in the circuit of Figure is equal to (a) 12 A (b) – 12 A (c) 4 A (d) None of the above

Q50. The voltage V in Figure is equal to (a) 3 V (b) – 3 V (c) 5 V (d) None of the above





Q51. The voltage V in Figure is always equal to

(a) 9 V (b) 5 V (c) 1 V (d) None of the above

Q52. In the circuit of Figure, the energy absorbed by the 4 Ω resistor in the time

interval (0, ∞) is (a) 36 joules (b) 16 joules (c) 256 joules (d) None of the above

Q53. In the circuit of Figure, the equivalent impedance seen across terminals a, b

is (a) (16/3) Ω (b) (8/3) Ω (c) (8/3 + 12j) Ω (d) None of the above

Q54. In the circuit of Figure, the current Di through the ideal diode (zero cut in

voltage and zero forward resistance) equals (a) 0 A (b) 4 A (c) 1 A (d) None of the above

Q55. The Hall angle θ of a metal sample is (a) Independent of the magnetic flux density B (b) Independent of the carrier mobility (c) Independent of the density of free carriers (d) Dependent on magnetic flux density, carrier mobility and density of free carriers Q56. The relaxation time (τ) in a perfect dielectric is (a) 0 (b) 1 (c) 1< τ < ∞ (d) ∞ Q57. The conductivity of a metal at ultraviolet frequency (1014Hz) approximately

equals (a) Infinity (b) Zero (c) DC conductivity (d) Half of DC conductivity





Q58. Constantan is an alloy composed of (a) 86% copper, 12% manganese and 2% nickel (b) 76% nickel, 21% chromium, 2% manganese and 1% iron (c) 60% copper and 40% nickel (d) 40% copper, 40% nickel and 20% carbon Q59. Assuming carrier mobility to be temperature independent, it can be shown

that pure Si(Eg = 1.1eV) and Ge (Eg = 0.7eV) have the same conductivity at a temperature of

(a) 191 K (b) 300 K (c) 471 K (d) 1470 K Q60. If the lattice temperature is increased then the Hall coefficient of a

semiconductor will (a) Decrease (b) Increase (c) First increase to a peak and then decrease (d) Remain constant Q61. The decreasing order of the electrical resistivities of nichrome, silicon and

diamond is (a) Nichrome, silicon, diamond (b) Silicon, diamond, nichrome (c) Diamond, nichrome, silicon (d) Diamond, silicon, nichrome Q62. An n-channel silicon (Eg = 1.1 eV) MOSFET was fabricated using n+ poly-

silicon gate and the threshold voltage was found to be 1 V. Now, if the gate is changed to p+ poly-silicon, other things remaining the same, the new threshold voltage should be

(a) -0.1 V (b) 0 V (c) 1.0 V (d) 2.1V Q63. A silicon nMOSFET has a threshold voltage of 1 V and oxide thickness of

400 oA [εr(SiO2) = 3.9, εo = 8.854 × 10-14 F/cm, q = 1.6 × 10-19 C]. The region

under the gate is ion implanted for threshold voltage tailoring. The dose and type of the implant (assumed to be a sheet charge at the interface) required shifting the threshold voltage to - 1 V are

(a) 1.08 × 1012/cm2, p – type (b) 1.08 × 1012/cm2, n – type (c) 5.4 × 1011/cm2, p – type (d) 5.4 × 1011/cm2, n –type Q64. A Zener diode in the circuit shown in Figure has a knee current of 5 mA,

and a maximum allowed power dissipation of 300 mW. What are the minimum and maximum load currents that can be drawn safely from the circuit, keeping the output voltage Vo constant at 6 V? (a) 0 mA, 180 mA (b) 5 mA, 110 mA (c) 10 mA, 55 mA (d) 60 mA, 180 mA

Q65. The drift velocity of electrons, in silicon, (a) Is proportional to the electric field for all values of electric field (b) Is independent of the electric field





(c) Increases at low values of electric field and decreases at high values of electric field exhibiting negative differential resistance

(d) Increases linearly with electric field at low values of electric field and gradually saturates at higher values of electric field

Q66. The diffusion potential across a P-N junction (a) Decreases with increasing doping concentration (b) Increases with decreasing band gap (c) Does not depend on doping concentration (d) Increases with increase in doping concentration Q67. The break down voltage of a transistor with its base open is BVCEO and that

with emitter open is BVCBO, then (a) BVCEO = BVCBO (b) BVCEO > BVCBO (c) BVCEO < BVCBO (d) BVCEO is not related to BVCBO. Q68. In a P type silicon sample, the hole concentration is 2.25 × 1015/cm3. If the

intrinsic carrier concentration is 1.5 × 1010/cm3, the electron concentration is

(a) zero (b) 1010/cm3 (c) 105/cm3 (d) 1.5 × 1025/cm3 Q69. In the transistor circuit shown in Figure below, collector-to-ground voltage

is + 20 V. Which of the following is the probable cause of error? (a) Collector-emitter terminals shorted (b) Emitter to ground connection open (c) 10 kΩ resistor open (d) Collector-base terminals shorted

Q70. The static characteristic of an adequately forward biased p-n junction is a

straight line, if the plot is of (a) log I vs. log V (b) log I vs. V (c) I vs. log V (d) I vs. V Q71. For a MOS capacitor fabricated on a p-type semiconductor, strong inversion

occurs when (a) Surface potential is equal to Fermi potential (b) Surface potential is zero (c) Surface potential is negative and equal to Fermi potential in magnitude (d) Surface potential is positive and equal to twice the Fermi potential. Q72. The probability that an electron in a metal occupies the Fermi-level, at any

temperature (> 0 K) (a) 0 (b) 1 (c) 0.5 (d) 1.5





Q73. A transistor having α = 0.99 and VBE = 0.7 V is used in the circuit shown in Figure. The value of the collector current will be .

(a) 1.39 mA (b) 3.7 mA (c) 5.33 mA (d) 7.73 mA

Q74. An n-p-n transistor under forward-active mode of operation is biased at IC =

1 mA, and has a total emitter-base capacitance Cπ of 12 pF, and the base transit time Fτ of 260 psec. Under this condition, the depletion capacitance of the emitter-base junction is . [use VT. 26mV]

(a) 2pF (b) 3pF (c) 4pF (d) 6pF Q75. The units of q/kT are (a) V (b) 1V − (c) J (d) J/K Q76. An n channel JFET has IDSS = 1 mA and Vp = -5 V. The maximum trans-

conductance is . (a) 0.2 m (b) 0.4 m (c) 0.6 m (a) 0.8 m Q77. The three values of a one-dimensional potential function φ shown in the given

Figure and satisfying Laplace equation are related as

( ) ( ) ( ) ( )3 1 1 3 1 3 1 3

2 2 2 22 2 2 2 3a b c d

3 3 3 2φ + φ φ + φ φ + φ φ + φ

φ = φ = φ = φ =

Q78. The electric field of a uniform plane wave is given by

( )8xE 10cos 3 t z a= π ×10 − π

Match List I with List II pertaining to the above wave and select the correct answer using the codes given below the lists:

List I List II (Parameters) (Values in MKS units) A. Phase velocity 1. 2 B. Wavelength 2. 3.14 C. Frequency 3. 377 D. Phase constant 4. 1.5 × 108 5. 3.0 × 108 Codes: A B C D A B C D





(a) 5 4 3 2 (b) 3 4 2 1 (c) 4 3 1 2 (d) 5 1 4 2 Q79. A loss less long transmission line charged to a voltage V and a capacitor C

charged to a voltage V/2 are shown in the given Figure. If the switch is closed at t = 0, the voltage V(t) across the capacitor for t ≥ 0 is given by

( ) ( ) ( ) ( )

( ) ( ) ( ) ( )

0 0

0

t tCZ CZ

tCZ

V Va V t 1 e b V t 2 e2 2

c V t 2 e d V t V, t 0

3V , t 04

− −

−

⎛ ⎞ ⎛ ⎞⎜ ⎟ ⎜ ⎟= − = −⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠

⎛ ⎞⎜ ⎟= − = >⎜ ⎟⎝ ⎠

= =

Q80. Two vectors A and B are such that A B nA,+ = where n is a positive scalar < 1. The angle between A and B is

( ) ( ) ( ) ( )3a b c d 22 4π π

π π

Q81. A lossless 50 Ω transmission line is terminated in (A) 25 Ω and (B) 100 Ω

loads. Which one of the following statements would be correct, if the voltage standing wave patterns measured in the two cases are compared?

(a) The two patterns will be identical in all respects and cannot be distinguished. (b) The two patterns will have identical locations of maxima/minima but the VSWR

will be higher in the case of A. (c) The two patterns will have identical locations of maxima/minima but the VSWR

will be higher in the case of B. (d) The two patterns will be identical except for a relative spatial shift of quarter

wavelength in the two cases. Q82. When the polarisation of the receiving antenna is unknown, to ensure that

it receives at least half the power (except in one particular situation), the transmitted wave should be

(a) Horizontally polarised (b) Vertically polarised (c) Circularly polarised (d) Elliptically polarised Q83. A parabolic dish has a diameter of 10 m. The maximum possible (ideal) gain

of the antenna at λ = 3.14 cm will be (a) 30 dB (b) 40 dB (c) 50 dB (d) 60 dB





Q84. The arrangement for calibrating a phase shifter is shown in the following diagram:

The calibrated short is adjusted while phase shift is introduced by the

phase shifter under test to maintain a null at the probe fixed in location. In one such measurement, the displacement of the short is 5 mm while the guide wavelength in it is 5 cm. At this setting of the phase shifter, the value of the phase shift (in degrees) will be

(a) 90 (b) 72 (c) 45 (d) 36 Q85. For time-varying electromagnetic fields with electric and magnetic field

given by E and H respectively, the rate of energy flow per unit area has a magnitude given by

( ) ( ) ( ) ( ) ( ) ( )a E H cos b E H sin c E H sin d E H cosθ θ + θ − θ 85. Q86. Consider the components of E and H listed below: x y z y z1. E 2. E 3. E 4. H 5.H For a plane wave traveling in x-direction and linearly polarized in y-

direction (a) 1, 2 and 5 exist (b) 1, 3 and 4 exist (c) 3 and 4 exist (d) 2 and 5 exist Q87. The expression for B , given that in free space ( )8

xE 15cos 6 10 t 2 z i= π × − π V/m is

( ) ( )( ) ( )( ) ( )( ) ( ) ( )

8 8y

8 8x

8 8y

8 8 8y z

a 5 10 cos 6 10 t 2 z i

b 90 10 sin 6 10 t 2 z i

c 45 10 sin 6 10 t 2 z i

d 5 10 cos 6 10 t 2 z i sin 6 10 t 2 z i

−

−

× π × − π

− π × π × − π

− × π × − π

⎡ ⎤× π × − π − π × − π⎣ ⎦

Q88. A wave is propagated in a parallel-plane wave-guide. The frequency is 6

GHz and plane separation is 3 cm. For the dominant mode match List I with List II and select the correct answer using the codes given below the lists:

List I List II (Quantities) (Numerical values) A. Cut-off wavelength (cm) 1. 5 B. Wavelength in wave guide (cm) 2. 6 C. Phase velocity (megametre/sec) 3. 9.05





D. Group velocity (megametre/sec) 4. 166 Codes 5. 543 A B C D A B C D (a) 1 2 5 4 (b) 2 1 4 3 (c) 2 1 5 4 (d) 5 4 2 3 Q89. A transmission line of 50 Ω characteristic impedance is terminated with a

100 Ω resistance. The minimum impedance measured on the line is equal to (a) 0 Ω (b) 25 Ω (c) 50 Ω (d) 100 Ω Q90. A parabolic dish antenna has a conical beam 2° wide. The directivity of the

antenna is approximately (a) 20 dB (b) 30 dB (c) 40 dB (d) 50 dB Q91. The skin depth at 10 MHz for a conductor is 1 cm. The phase velocity of an

electromagnetic wave in the conductor at 1000 MHz is about ( ) ( ) ( ) ( )6 7 8 8a 6 10 m / s b 6 10 m / s c 3 10 m/s d 6 10 m/s× × × × Q92. The intrinsic impedance of copper at high frequencies is (a) Purely resistive (b) Purely inductive (c) Complex with a capacitive component (d) Complex with an inductive component Q93. All transmission line sections in Figure have a characteristic impedance R0

+ j0. The input impedance Zin equals

( ) ( ) ( ) ( )0 0 0 0

2 3a R b R c R d 2R3 2

Q94. The time averaged Poynting vector, in W/m2, for a wave with ( )j t+ z

yE 24e aω β= V/m in free space is

( ) ( ) ( ) ( )z z z z2 2.4 4.8 4.8a a b a c a d a− −π π π π

Q95. The wavelength of a wave with propagation constant (0.1 π + j 0.2 π) m-1 is

( ) ( ) ( ) ( )2a m b 10 m c 20 m d 30 m0.05





Q96. The depth of penetration of a wave in a lossy dielectric increases with

increasing (a) Conductivity (b) Permeability (c) Wavelength (d) Permittivity Q97. The polarisation of a wave with electric field vector ( ) ( )j t z

x y0E E e a aω − β= + is (a) Linear (b) Elliptical (c) Left hand circular (d) Right hand circular Q98. The radiation resistance of a circular loop of one turn is 0.01 Ω. The

radiation resistance of five turns of such a loop will be (a) 0.002 Ω (b) 0.01 Ω (c) 0.05 Ω (d) 0.25 Ω Q99. An antenna in free space receives 2 μW of power when the incident electric

field is 20 mV/m rms. The effective aperture of the antenna is (a) 0.005 m2 (b) 0.05 m2 (c) 1.885 m2 (d) 3.77 m2 Q100. The maximum usable frequency of an ionospheric layer at 60° incidence

and with 8 MHz critical frequency is

(a) 16 MHz (b) 16 MHz3

(c) 8 MHz (d) about 6.93 MHz

Q101. Bond strength of secondary bonds is in the range of (a) 1 kJ/mol (b) 10 kJ/mol (c) 100 kJ/mol (d) 1000 kJ/mol Q102. Electron sea exists in (a) Polar bonds (b) Ionic bond (c) Covalent bond (d) Metallic bond Q103. Coordination number for closest packed crystal structure (a) 16 (b) 12 (c) 8 (d) 4 Q104. Pick the thermo-plast from the following (a) Vinyls (b) Epoxies (c) Resins (d) Vulcanized rubber Q105. Schottky-defect in ceramic material is (a) Interstitial impurity (b) Vacancy- interstitial pair of cations (c) Pair of nearby cation and anion vacancies (d) Substitutional impurity Q106. Basic source of magnetism ______________. (a) Charged particles alone (b) Movement of charged particles (c) Magnetic dipoles (d) Magnetic domains Q107. Match list-1 with list-2: List-1 List-2 1. Dia-magnetic (A) superconductors 2. Para-magnetic (B) alkali metals 3. Ferro-magnetic (C) transition metals





4. Ferri-magnetic (D) ferrite (a) A-1,B-2,C-3,D-4 (b)A-1,B-2,C-4,D-3 (c) A-2,B-1,C-3,D-4 (d)A-2,B-1,C-4,D-3 Q108. Magnetic susceptibility ferro-magnetic materials is (a) +10−5 (b) -10−5 (c) 105 (d) 10−5 to 10−2 Q109. Typical size of magnetic domains ______ (mm). (a) 1-10 (b) 0.1-1 (c) 0.05 (d) 0.001 Q110. Which one of the following is soft magnet? (a) 45 Permalloy (b) CrO2 (c) Fe-Pd (d) Alnico Q111. Example for magnetic material used in data storage devices (a) 45 Permalloy (b) CrO2 (c) Cunife (d) Alnico Q112. Flow of electrons is affected by the following (a) Thermal vibrations (b) Impurity atoms (c) Crystal defects (d) all Q113. Fermi energy level for p-type extrinsic semiconductors lies (a) At middle of the band gap (b) Close to conduction band (c) Close to valence band (d) None Q114. Fermi level for extrinsic semiconductor depends on (a) Donor element (b) Impurity concentration (c) Temperature (d) All Q115. High dielectric constant material is must for __________. (a) Insulation of wires (b) Generators (c) Switch bases (d) Generators. Q116. Dielectric constant for most polymers lies in the range of _______. (a) 1-3 (b) 2-5 (c) 4-7 (d) 6-10. Q117. Example for piezo-electric material (a) Rochelle salt (b) Lead zirconate (c) Potassium niobate (d) Barium Titanium oxide Q118. The angle between [111] and [11−2] directions in a cubic crystal is (in

degrees) (a) 0 (b) 45 (c) 90 (d) 180 Q119. Miller indices of the line of intersection of (−1−11) and (110) are (a) [110] (b) [101] (c) [10−1] (d) [−110]

Q120. Copper behaves as a: (a) Conductor always (b) Conductor or dielectric depending on the applied electric field strength (c) Conductor or dielectric depending on the frequency (d) Conductor or dielectric depending on the electric current density





Answer 1. Ans. (a) 2. Ans. (b) 3. Ans. (a) 4. Ans. (a) 5. Ans. (d) 6. Ans. (c) 7. Ans. (d) 8. Ans. (c) 9. Ans. (c) 10. Ans. (c) 11. Ans. (d) 12. Ans. (a) 13. Ans. (b) 14. Ans. (c) 15. Ans. (c) 16. Ans. (b) 17. Ans. (c) 18. Ans. (a) 19. Ans. (a) 20. Ans. (d) 21. Ans. (a) 22. Ans. (a) 23. Ans. (b) 24. Ans. (b) 25. Ans. (d) 26. Ans. (c) 27. Ans. (b) 28. Ans. (a) 29. Ans. (a) 30. Ans. (c) 31. Ans. (a) 32. Ans. (c) 33. Ans. (a) 34. Ans. (a) 35. Ans. (a) 36. Ans. (b) 37. Ans. (d) 38. Ans. (c) 39. Ans. (c) 40. Ans. (a)

41. Ans. (b) 42. Ans. (a) 43. Ans. (b) 44. Ans. (d) 45. Ans. (a) 46. Ans. (a) 47. Ans. (b) 48. Ans. (a) 49. Ans. (b) 50. Ans. (a) 51. Ans. (a) 52. Ans. (b) 53. Ans. (b) 54. Ans. (c) 55. Ans. (d) 56. Ans. (d) 57. Ans. (b) 58. Ans. (c) 59. Ans. (c) 60. Ans. (a) 61. Ans. (d) 62. Ans. (c) 63. Ans. (a) 64. Ans. (c) 65. Ans. (d 66. Ans. (d) 67. Ans. (c) 68. Ans. (c) 69. Ans. (b) 70. Ans. (b) 71. Ans. (d) 72. Ans. (b) 73. Ans. (c) 74. Ans. (a) 75. Ans. (b) 76. Ans. (b) 77. Ans. (a) 78. Ans. (d) 79. Ans. (a) 80. Ans. (c)

81. Ans. (a) 82. Ans. (c) 83. Ans. (d) 84. Ans. (b) 85. Ans. (b) 86. Ans. (d) 87. Ans. (a) 88. Ans. (c) 89. Ans. (d) 90. Ans. (a) 91. Ans. (a) 92. Ans. (a) 93. Ans. (b) 94. Ans. (a) 95. Ans. (b) 96. Ans. (c) 97. Ans. (c) 98. Ans. (b) 99. Ans. (c)

100. Ans. (b) 101. Ans. (b) 102. Ans. (d) 103. Ans. (b) 104. Ans. (a) 105. Ans. (c) 106. Ans. (b) 107. Ans. (a) 108. Ans. (c) 109. Ans. (c) 110. Ans. (a) 111. Ans. (b) 112. Ans. (d) 113. Ans. (b) 114. Ans. (d) 115. Ans. (a) 116. Ans. (c) 117. Ans. (b) 118. Ans. (c) 119. Ans. (d)

120. Ans. (a)

india’s no 1 ies-2010 ies academy et (paper-i) paper i ies 2010.pdfindia’s no 1 ies-2010 ies...

Documents