GATE 2005 EC Solved Paper

3.A fair dice is rolled twice. The probability that anodd number will follow an even
number is
a)1/2
(b)1/6
(c)1/3
(d)1/4

11. The band gap of Silicon at room temperature is:
(a) 1.3 eV (b) 0.7 eV (c) 1.1 eV (d) 1.4 eV

12. A Silicon PN junction at a temperature of 20°C has a reverse saturation current of 10 pico-Amperes (pA). The reverse saturation current at 40°C for the same bias
is approximately
(a) 30 pA (b) 40 pA (c) 50 pA (d) 60 pA

13. The primary reason for the widespread use of Silicon in semiconductor device
technology is
(a) abundance of Silicon on the surface of the Earth.
(b) larger bandgap of Silicon in comparison to Germanium.
(c) favorable properties of Silicon-dioxide (SiO2)
(d) lower melting point

14. The effect of current shunt feedback in an amplifier is to
(a) increase the input resistance and decrease the output resistance.
(b) increase both input and output resistances.
(c) decreases both input and output resistances.
(d) decrease the input resistance and increase the output resistance

16. The first and the last critical frequency of an RC-driving point impedance function
must respectively be
(a) a zero and a pole (b) a zero and a zero
(c) a pole and a pole (d) a pole and a zero

17. The cascode amplifier is a multistage configuration of
(a) CC-CB (b) CE-CB (c) CB-CC (d) CE-CC

18. Decimal 43 in Hexadecimal and BCD number system is respectively
(a) B2, 0100 0011 (b) 2B, 0100 0011
(c) 2B, 0011 0100 (d) B2, 0100 0100

24. Which of the following analog modulation scheme requires the minimum
transmitted power and minimum channel bandwidth?
(a) VSB (b) DSB-SC (c) SSB (d) AM

27. Despite the presence of negative feedback, control systems still have problems of
instability because the
(a) components used have nonlinearities.
(b) dynamic equations of the subsystems are not known exactly.
(c) mathematical analysis involves approximations.
(d) system has large negative phase angle at high frequencies.

30. Refractive index of glass is 1.5. Find the wavelength of a beam of light with a
frequency of 1014 Hz in glass. Assume velocity of light is 3×108 m/s in vacuum.
(a) 3 µm (b) 3 mm (c) 2 µm (d) 1 µm

36. Match the following and choose the correct combination:

Group 1 Group 2
E. Newton –Raphson method 1. Solving nonlinear equations
F. Runge-Kutta method 2. Solving linear simultaneous equations
G. Simpson’s Rule 3. Solving ordinary differential equations
H. Gauss elimination 4. Numerical integration
5. Interpolation
6. Calculation of Eigen values
(a) E – 6 F – 1 G – 5 H - 3 (b) E – 1 F – 6 G – 4 H - 3
(c) E – 1 F – 3 G – 4 H - 2 (d) E – 5 F – 3 G – 4 H - 1

45. A Silicon PN junction diode under reverse bias has depletion region of width 10
µm. The relative permittivity of Silicon,εr= 11.7 and the permittivity of free space
εd=8.85X10-12 f/m The depletion capacitance of the diode per square meter is
(a) 100 µF (b) 10 µF (c) 1 µF (d) 20 µF

56. The present output Qn of an edge triggered JK flip-flop is logic 0. If J=1, then Qn+1
(a) cannot be determined (b) will be logic 0
(c) will be logic 1 (d) will race around

69. A MOS capacitor made using p type substrate is in the accumulation mode. The
dominant charge in the channel is due to the presence of
(a) holes (b) electrons
(c) positively charged ions (d) negatively charged ions

73. A carrier is phase modulated (PM) with frequency deviation of 10 kHz by a single
tone frequency of 1 kHz. If the single tone frequency is increased to 2 kHz,
assuming that phase deviation remains unchanged, the bandwidth of the PM
signal is
(a) 21 kHz (b) 22 kHz (c) 42 kHz (d) 44 kHz


76. Characteristic impedance of a transmission line is 50 Ω.Input impedance of the
open circuited line is Zoc=100+j150Ω.When the transmission line is shortcircuited the value of the input impedance will be
(a) 50 Ω (b) 100 + j150Ω
(c) 7.69 + j11.54 Ω (d) 7.69 – j11.54

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