EIL- Technical Questions

Engineers India Limited (EIL) -2012

1. The eigen values of a skew-symmetric matrix are
(A) always zero 
(B) always pure imaginary
(C) either zero or pure imaginary 
(D) always real
2. The trigonometric Fourier series for the waveform f(t) shown below contains


(A) only cosine terms and zero value for the dc component
(B) only cosine terms and a positive value for the dc component
(C) only cosine terms and a negative value for the dc component
(D) only sine terms and a negative for the dc component

3.A function n(x) satisfied the differential equation (d2n(x)/dx2)-n(x)/L2=0 where L is a constant. The boundary conditions are: n(0)=K and n ( ∞ ) = 0. The solution to this equation is
(A) n(x) = K exp(x/L) 
(B) n(x) = K exp(-x/ L )
(C) n(x) = K2 exp(-x/L) 
(D) n(x) = K exp(-x/L)

4. For parallel RLC circuit, which one of the following statements is NOT correct?
(A) The bandwidth of the circuit deceases if R is increased
(B) The bandwidth of the circuit remains same if L is increased
(C) At resonance, input impedance is a real quantity
(D) At resonance, the magnitude of input impedance attains its minimum value.

5. At room temperature, a possible value for the mobility of electrons in the inversion
layer of a silicon n-channel MOSFET is
(A) 450 cm2/V-s 
(B) 1350 cm2/V-s 
(C) 1800 cm2/V-s 
(D) 3600 cm2/V-s

6. Thin gate oxide in a CMOS process in preferably grown using
(A) wet oxidation 
(B) dry oxidation
(C) epitaxial deposition 
(D) ion implantation

9. For the output F to be 1 in the logic circuit shown, the input combination should be

(A) A = 1, B= 1. C = 0 
(B) A = 1, B= 0,C = 0
(C) A = 0, B= 1. C = 0 
(D) A = 0, B= 0, C = 1

10.For an N-point FFT algorithm with N = 2m which one of the following statements is TRUE?
(A) It is not possible to construct a signal flow graph with both input and output in normal order
(B) The number of butterflies in the mth stage is N/m
(C) In-place computation requires storage of only 2N node data
(D) Computation of a butterfly requires only one complex multiplication

11. Consider an angle modulated signal x(t) = 6cos[2πx106t+2sin(8000πt) +
4cos(8000pt)] V. The average power of x(t) is.
(A) 10W 
(B) 18W 
(C) 20W 
(D) 28W

12.A transmission line has a characteristic impedance of 50 Ω and a resistance of 0.1 Ω /m. if the line is distortion less, the attenuation constant (in Np/m) is
(A) 500 
(B) 5 
(C) 0.014 
(D) 0.002

13.The electric field component of a time harmonic plane EM wave traveling in a nonmagnetic loss less dielectric medium has an amplitude of 1 V/m. If the relative permitivity of the medium is 4, the magnitude of the time-average power density
vector (in W/m2) is
(A)1/30π
(B)1/60π
(C)1/120π
(D)1/240π

14.Suppose that the modulating signal is m(t) = 2cos (2π fmt) and the carrier signal is xC(t) = AC cos(2πfct),which one of the following is a conventional AM signal without over-modulation?
(A) x(t) = Acm(t) cos(2πfct)
(B) x(t) = Ac[1 + m(t)]cos(2πfct)
(C) x(t) = Ac cos(2πfct) + Ac/4m(t) cos(2πfct)
(D) x(t) = Ac cos(2πfmt) cos(2πfct) + Ac sin(2πfmt) sin(2πfct)