BHEL Supervisor Trainee ECE Exam Paper

Will you please provide the question paper of BHEL Supervisor Trainee ECE Exam ?

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Here I am providing the list of few questions of BHEL Supervisor Trainee ECE Exam which you are looking for.
1. Consider the following statements regarding the complex Poynting vector P
for the power radiated by a point source in an infinite homogeneous and lossless medium. ( ) Re P

denotes the real part of P

. S denotes a spherical surface whose
centre is at the point source, and ɵn
denotes the unit surface normal on S. Which
of the following statements is TRUE?
(A) ( ) Re P

remains constant at any radial distance from the source
(B) ( ) Re P

increases with increasing radial distance from the source
(C) ( )
s
Re P .ndS ∫∫

remains constant at any radial distance from the source
(D) ( )
s
Re P .ndS ∫∫

decreases with increasing radial distance form the source

2. A transmission line of characteristic impedance 50W is terminated by a 50W load.
When excited by a sinusoidal voltage source at 10GHz, the phase difference
between two points spaced 2mm apart on the line is found to be
4
p
radians. The
phase velocity of the wave along the line is
(A) 8 0.8 10 m/ s × (B) 8 1.2 10 m/ s × (C) 8 1.6 10 m/ s × (D) 8 3 10 m/ s ×
Answer: - (C)
Exp: - 0 Z 50 = W; L Z 50 = W
For
4
p
radians the distance is 2mm

3. An analog signal is band-limited to 4kHz, sampled at the Nyquist rate and the
samples are quantized into 4 levels. The quantized levels are assumed to be
independent and equally probable. If we transmit two quantized samples per
second, the information rate is ________ bits / second.
(A) 1 (B) 2 (C) 3 (D) 4
Answer: - (D)
Exp: - Since two samples are transmitted and each sample has 2 bits of information,
then the information rate is 4 bits/sec.
½EC-Paper Code-B½ GATE 2011

4. The root locus plot for a system is given below. The open loop transfer function
corresponding to this plot is given by
Exp: - ' x ' ® indicates pole
'O' ® indicates zero
The point on the root locus when the number of poles and zeroes on the real axis
to the right side of that point must be odd

5. A system is defined by its impulse response ( ) ( ) n h n 2 u n 2 = − . The system is
(A) stable and causal (B) causal but not stable
(C) stable but not causal (D) unstable and non-causal
Answer: - (B)
Exp: - ( ) ( ) n h n 2 u n 2 = −
( ) h n is existing for n>2 ; so that ( ) h n 0;n 0 = < ⇒ causal
( ) ( ) n n
n n n 2
h n 2 u n 2 2
¥ ¥ ¥
=−¥ =¥ =
= − = = ¥ ⇒ ∑ ∑ ∑ System is unstable

6. If the unit step response of a network is ( ) t 1 e−a − , then its unit impulse response
is
(A) t e−a a (B) 1 t e − −a a (C) ( ) 1 t 1 e − −a − a (D) ( ) t 1 e−a − a
Answer: - (A)
Exp: - ( ) S t ® step response
Impulse response ( ) ( ) ( ) ( ) t t d d
h t S t 1 e e
dt dt
a a = = − = a

7. The output Y in the circuit below is always ‘1’ when
× × × o
jw
s
0 1 − 2 − 3 −
P
Q
R
Y

(A) two or more of the inputs P,Q,R are ‘0’
(B) two or more of the inputs P,Q,R are ‘1’
(C) any odd number of the inputs P,Q,R is ‘0’
(D) any odd number of the inputs P,Q,R is ‘1’
Answer: - (B)
Exp: - The output Y expression in the Ckt
Y PQ PR RQ = + +
So that two or more inputs are ‘1’, Y is always ‘1’.

8. In the circuit shown below, capacitors C1 and C2 are very large and are shorts at
the input frequency. i v is a small signal input. The gain magnitude o
i
v
v
at 10M
rad/s is
(A) maximum (B) minimum (C) unity (D) zero
Answer: - (A)
Exp: - In the parallel RLC Ckt
L 10 H = µ andC 1nF =
7
g
6 9
1 1
10 rad / s 10Mrad / s
LC 10 10 10 − −
w = = = =
× ×
So that for a tuned amplifier, gain is maximum at resonant frequency

9. Drift current in the semiconductors depends upon
(A) only the electric field
(B) only the carrier concentration gradient
(C) both the electric field and the carrier concentration
(D) both the electric field and the carrier concentration gradient
Answer: - (C)
Exp: - Drift current, J E = s
( ) n P J n p qE = µ + µ
So that it depends on carrier concentration and electric field.
~
+
−
+
−
2kW
+
2 C
1 Q
o v
1 C 2kW
i v
2.7V
2kW
2kW
10 H µ
5V

10. A Zener diode, when used in voltage stabilization circuits, is biased in
(A) reverse bias region below the breakdown voltage
(B) reverse breakdown region
(C) forward bias region
(D) forward bias constant current mode