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Aptitude Test
Bank Exams
Engineering
MBA Exams
Psc
Upsc
EC
1
In a MOSFET operating in the saturation region, the channel length modulation effect causes
an increase in the gatesource capacitance
a decrease in the Transconductance
a decrease in the unitygain cutoff frequency
a decrease in the output resistance
2
The return loss of a device is found to be 20 dB. The voltage standing wave ratio (VSWR) and magnitude of reflection coefficient are respectively
1.22 and 0.1
0.81 and 0.1
1.22 and 0.1
2.44 and 0.2
3
A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches irrespective of the state of the other switch. The logic of switching of the bulb resembles
an AND gate
an OR gate
an XOR gate
a NAND gate
4
For a periodic signal v (t) = 30sin100t + 10cos300t + 6 sin(500t + π / 4) , the fundamental frequency in rad/s
100
300
500
1500
5
The minimum Eigen value of the following matrix is
0
1
2
3
6
The transfer function V
_{2}
(S)/V
_{1}
(s) of the circuit shown below is
(0.5s+1)/(s+1)
(3s+6)/(s+2)
(s+2)/(s+1)
(s+1)+(s+2)
7
in the circuit shown below, the knee current of the ideal Zener diode is 10 mA. To maintain 5v across R
_{L}
, the minimum value of R
_{L}
, in ohm and the minimum power rating of the Zener diode in mW, respectively, are
125 and 125
125 ad 250
250 and 125
250 and 250
8
The bit rate of a digital communication system is R kbits/s. The modulation used is 32QAM. The minimum bandwidth required for ISI free transmission is
R/10 Hz
R/10 kHz
R/5 Hz
R/5 kHz
9
Consider a delta connection of resistors and its equivalent star connection as shown below. If all elements of the delta connection are scaled by a factor k,k>0, the elements of the corresponding star equivalent will be scaled by a factor of
(A)
(B)
(C)
(D)
10
*
In the circuit shown below what is the output voltage (V
_{out}
) if a silicon transistor Q and a ideal opamp are used?
15v
0.7v
+0.7v
+15v
11
Assuming zero initial condition, the response y(t) of the system given below to a unit step input u(t) is
(A)
(B)
(C)
(D)
12
The Bode plot of a transfer function G (s) is shown in the figure below
(A)
(B)
(C)
(D)
13
The maximum value of q until which the approximation Sin θ ~ θ holds to within 10% error is
10 °
18 °
50 °
90 °
14
A source v
_{s }
3
4
5
7
15
Which one of the following statements is NOT TRUE for a continuous time causal and stable LTI system?
All the poles of the system must lie on the left side of the jω axis
Zeros of the system can lie anywhere in the splane
All the poles must lie within ΙsΙ = 1
All the roots of the characteristic equation must be located on the left side of the jω axis
16
In a voltage voltage feedback as shown below, which one of the following statements is TRUE if the gain k is increased?
the input impedance increases and output impedance decreases
The input impedances increases and output impedance also increases
The input impedance decreases and output impedance also decreases
The input impedance decreases and output impedance increases
17
Two systems with impulse responses h1(t) and h2(t) are connected in cascade. Then the overall impulse response of the cascaded system is given by
Product of h1(t) and h2(t)
Sum of h1(t) and h2(t)
Convolution of h1(t) and h2(t)
Subtraction of h1(t) and h2(t)
18
For 8085 microprocessor, the following program is executed MVI A, 05H; MVIB, 05H; PTR: ADD B; DCR B; JNZ PTR; ADI 03H; HLT; At the end of program, accumulator contains
17 H
20 H
23 H
05 H
19
A polynomial f(x)= a
_{4}
x
^{4}
+a
_{3}
x
^{3}
+a
_{2}
x
^{2}
+a
xa
_{0}
with all coefficients positive has
no real roots
no negative real root
odd number of real roots
atleast one positive and one negative real root
20
In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or water vapor) produces
superior quality oxide with a higher growth rate
inferior quality oxide with a higher growth rate
inferior quality oxide with a lower growth rate
superior quality oxide with a lower growth rate
None of these
21
A bandlimited signal with a maximum frequency of 5 kHz is to be sampled. According to the sampling theorem, the sampling frequency which is not valid is
5 kHz
12 kHz
15 kHz
20 kHz
22
Let A be an m x n matrix and B be n x m matrix. It is given that determinant (I
_{m}
+ AB) = determinant (I
_{n}
+BA), where I
_{k}
is the k x k identity matrix. Using the above property , the determinant of the matrix given below is
2
5
8
16
23
Let U and V be two independent zero mean Gaussian random variables of variances 1/4 and 1/9respectively. The probability P(3V>=2U) is
4/9
1/2
2/3
5/9
24
Let g(t)=e
^{πt2}
, and h(t) is a filter matched to g(t). If g(t) is applied to h(t), then the Fourier transform of the output is
(A)
(B)
(C)
(D)
25
In a forward biased pn junction diode, the sequence of events that best describes the mechanism of current flow is
injection, and subsequent diffusion and recombination of minority carriers
injection, and subsequent drift and generation of minority carriers
extraction, and subsequent diffusion and generation of minority carriers
extraction, and subsequent drift and recombination of minority carriers
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