EC GATE 2013 (Test 3)



Tag: ec gate 2013
Q.1
Choose the grammatically CORRECT sentence:
A. Two and two add four
B. Two and two become four
C. Two and two are four
D. Two and two make four
Answer : Option D
Explaination / Solution:
No Explaination.


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Topic: Arithmetic Tag: EC GATE 2013
Q.2
Find the sum to n terms of the series 10+84+734+......
A.
B.
C.
D.
Answer : Option D
Explaination / Solution:
No Explaination.


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Q.3
The DFT of a vector [a b c d] is the vector [α β γ δ]. Consider the product 
 
The DFT of the vector [p q r s] is a scaled version of
A. 2 β2 γ2 δ2]
B. [α β γ δ]
C. [α+β β+δ δ+γ γ+α]
D. [α β γ δ]
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.4
In a forward biased pn junction diode, the sequence of events that best describes the mechanism of current flow is
A. injection, and subsequent diffusion and recombination of minority carriers
B. injection, and subsequent drift and generation of minority carriers
C. extraction, and subsequent diffusion and generation of minority carriers
D. extraction, and subsequent drift and recombination of minority carriers
Answer : Option A
Explaination / Solution:

The potential barrier of the pn junction is lowered when a forward bias voltage is applied, allowing electrons and holes to flow across the space charge region (Injection) when holes flow from the p region across the space charge region into the n region, they become excess minority carrier holes and are subject to diffuse, drift and recombination processes. Hence correct option is (A)

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Q.5
The ac schematic of an NMOS common-source state is shown in the figure below, where part of the biasing circuits has been omitted for simplicity. For the n-channel MOSFET M, the transconductance  and body effect and channel length modulation effect are to be neglected. The lower cutoff frequency in HZ of the circuit is approximately at

A. 8
B. 32
C. 50
D. 200
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.6
Two magnetically uncoupled inductive coils have Q factors q1 and q2 at the chosen operating frequency. Their respective resistances are R1 and R2. When connected in series, their effective Q factor at the same operating frequency is
A. q1 + q2
B. (1/q1) + (1/q2)
C. (q1R1 + q2R2) / (R1 + R2)
D. (q1R2 + q2R1) / (R1 + R2)
Answer : Option C
Explaination / Solution:

The quality factor of the inductances are given by

So, in series circuit, the effective quality factor is given by


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Q.7
The signal flow graph for a system is given below. The transfer function Y(s)/U(s) for this system is

A.
B.
C.
D.
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.8
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. k2
D.
Answer : Option B
Explaination / Solution:

In the equivalent star connection, the resistance can be given as 


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Q.9
A voltage 1000 sin𝜔t Volts is applied across YZ . Assuming ideal diodes, the voltage measured across WX in Volts, is

A. sin𝜔t
B. (sin𝜔t + |sin𝜔t|)/2
C. (sin𝜔t - sin𝜔t/2
D. 0 for all t
Answer : Option D
Explaination / Solution:
No Explaination.


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Q.10
Let U and V be two independent zero mean Gaussain random variables of variances 1/4 and 1/9 respectively.  The probability  is
A. 4/9
B. 1/2
C. 2/3
D. 5/9
Answer : Option B
Explaination / Solution:
No Explaination.


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