Quiz Electronics Engineering 3 Nov 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 03/11/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Let P(E) denote the probability of the event E. Given P(A) = 1, P(B) = 1/2 the values of P(A/B) and P(B/A) respectively are
(a) 1 , 1/2
(b) 1/2, 1/4
(c) 1/2 , 1
(d) 1/4, 1/2

Q2. Introduction of +ve feedback in an amplifier
(a) increases the voltage gain
(b) initiates oscillations to occur
(c) is not possible
(d) decreases the voltage gain

Q3. In a network made up of linear resistors and ideal voltage sources, values of all resistors are doubled. Then the voltage across each resistor is.
(a) Doubled
(b) Halved
(c) Not changed
(d) Decreased four times

Q4. Evaluate (X ⊕ Y) ⊕ Y
(a) All 1’s
(b) All O’s
(c) Y
(d) X

Q5. The point form of the relation connecting vector magnetic potential A ⃗ and current density J ⃗ is
(a) ∇^2 A ⃗ = -µ_o J ⃗
(b) A ⃗ = ∫▒(µ_o J ⃗)/4πεRdv
(c) ∇ × A ⃗ = J ⃗ + (∂D ⃗)/∂t
(d) (∂A ⃗)/∂t = -J ⃗/σ

Q6. If a continuous time signal x(t) can take on any value in the continuous interval(-∞, ∞), it is called
(a) Deterministic signal
(b) analog signal
(c) random signal
(d) digital signal

Q7. In order to prevent overloading of the last IF amplifier in a receiver, one should use
(a) Squelch
(b) Double conversion
(c) Variable sensitivity
(d) Variable selectivity

Q8. An intrinsic semiconductor at absolute zero temperature
(a) has a large number of holes.
(b) behaves like an insulator.
(c) behaves like a metallic conductor.
(d) has few holes and same number of electrons.

Q9. What is the length of SP(Stack Pointer)?
(a) 16 bits
(b) 12 bits
(c) 8 bits
(d) 6 bits

Q10. Three or more devices share a link in _________ connection.
(a) Unipoint
(b) Polar point
(c) Point to point
(d) Multipoint

SOLUTIONS
S1. Ans.(a)
Sol. Given:
P (A) = 1
P (B) =1/2
Both events are independent
⇒ P(A∩B) = 1/2
Now,
P(A\B) = P(A∩B)/P(B)
∴ P(A\B) = (1/2)/(1/2)=1
and P(B\A) = P(A∩B)/P(A)
∴ P(B\A) = (1/2)/1= 1/2

S2. Ans.(b)
Sol. The positive feedback increases the gain of the amplifier. It has the disadvantages of increased distortion and instability. So, It is not used in amplifier. It is used in oscillators. If positive feedback is sufficient large, it leads to oscillations.

S3. Ans.(c)
Sol. If value of resistors changes then current flowing through it also changes because high resistance decreases flow of current and low resistance allow more current to flow through it. Hence, Voltage remains constant.

S4. Ans.(d)
Sol.
(X ⊕ Y) ⊕ Y = [X`Y+XY`]⊕ Y [Applying XOR operation]
= [X`Y+XY`]Y` + [X`Y+XY`]`Y
= [X`Y+XY`]Y` + [XY+X`Y`]Y [XOR + Inverter = XNOR]
= X`YY` + XY`Y` + XYY + X`Y`Y
= 0 + XY` + XY + 0 [YY`=Y; Y`Y`=Y`; YY=Y; Y`Y=0 ]
= X(Y+Y`) = X

S5. Ans.(a)

S6. Ans.(b)

S7. Ans.(c)
Sol. In order to prevent overloading of the last IF amplifier in a receiver, one should use Variable sensitivity.

S8. Ans. (b)
Sol. An intrinsic semiconductor at absolute zero temperature behaves as an Insulator because no charge carriers flow at T = 0K. All electrons lie in the VB and they don’t have sufficient energy to jump to conduction band.

S9. Ans.(a)
Sol. Stack Pointer is a part of Stack register. It is used to store data or address during the execution of sub program so that processor can easily return to main program after the execution of the sub program. The physical address for read and write in stack is obtained by adding content of stack pointer with the base address of stack segment.

S10. Ans.(d)