Quiz Electronics Engineering 5 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 05/10/2020

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

Q1. The poles of a digital filter with linear phase response can lie
(a) only at z = 0
(b) only on the unit circle
(c) only inside the unit circle but not a t z = 0
(d) on the left side of Real(z) = 0 line.

Q2. The effect of using freewheeling diode are:
1. The load performance is improved.
2. The system efficiency is improved.
3. It prevents the output voltage from becoming negative.
Which of the following are Correct?
(a) 1 and 2
(b) 1 and 3
(c) 1,2 and 3
(d) 2 and 3

Q3. Parity bit is used in the
(a) self-checking codes
(b) self-complementing codes
(c) self-complementing non -weighted codes
(d) self-checking and correcting codes

Q4. In a pure resistive circuit, the instantaneous voltage and current are given by:
V = 250 sin 314 t volts
I = 10 sin 314 t Amp
The peak power in the circuit is ……..
(a) 1250 W
(b) 2500 W
(c) 25 W
(d) 250 W

Q5. WAN stands for __________
(a) Wide Area Network
(b) World Area Network
(c) Web Area Network
(d) Web Access Network

Q6. The quantization noise of a PCM system depends on
(a) Number of quantization levels
(b) Step-size
(c) Both step-size and number of quantization levels
(d) Sampling rate

Q7. In 8085 microprocessor, the flag register have ______ status indicator.
(a) 1
(b) 2
(c) 4
(d) 5

Q8. Consider the following statements:
Electromagnetic waves are refracted when they
1. pass through a medium of different permittivity.
2. pass through a small slot in a dielectric slab.
3. are incident on a perfectly conducting surface.
Which of these statements is/are correct?
(a) 1 only
(b) 2 only
(c) 3 only
(d) 1 and 3

Q9. If X(z) is 1/(1-z^(-1) ) with |z| > 1, then what is the corresponding x[n]?
(a) e^(-n)
(b) e^n
(c) u(n)
(d) 𝛿(n)

Q10. β€œThe output is β€˜0’ for like inputs and β€˜1’ for unlike inputs”. This statement is representative of which logic gate?
(a) OR
(b) EX-OR
(c) NAND
(d) AND

SOLUTIONS

S1. Ans.(a)
Sol. In a linear phase response,
β‡’ y[n] = kx[n – k]
Z-transform of given function is –
β‡’ Y[z] = kz^(-k)X[z]
β‡’ Y[z]/(X[z]) = kz^(-k)
∴ H[z] = kz^(-k)
Hence, Transfer function has only one pole at the origin z = 0.

S2. Ans.(c)

S3. Ans (d)
Sol. A parity bit, or check bit, is a bit added to a string of binary code to ensure that the total number of 1-bits in the string is even or odd. Parity bits are used so that later at the output it can be verified that the sent data and received data are same. So, it is used for checking and correcting codes.

S4. Ans.(b)
Sol. Given:
V = 250 sin314t volts
I = 10 sin314t Amp
Peak power = VP Γ— IP = 250 Γ— 10 = 2500 watt
where,
VP = Peak voltage = 250 Volts
IP = Peak current = 10 Amp.

S5. Ans.(a)
Sol. WAN stands for Wide Area Network.
coverage area can be a country or continent.
It may be very simple or complex depending on usage.
These can be connected through cable lines or satellites.

S6. Ans.(c)
Sol. We know that, Quantization noise power is
NQ = Ξ”^2/12
where,
Ξ” = (Dynamic Range)/L
Therefore, Quantization Noise depends on both step-size and no. of quantization levels.

S7. Ans.(d)
Sol. There are 5 status indicator in 8085 microprocessor. Those are Sign Flag(S), Zero Flag(Z), Auxiliary Carry Flag(AC), Parity Flag(P) and Carry Flag(CY). These registers indicates the status of the accumulator and other registers when Arithmetic and Logic operation is performed in the microprocessor. It β€˜Set’ or β€˜Reset’ the flag depending upon the result.

S8. Ans.(a)
Sol.
Refraction in EM waves takes place when it passes through a medium of different permittivity.
Diffraction in EM waves takes place when it passes through a small slot in a dielectric slab.
Reflection in EM waves takes place when it is incident on a perfectly conducting surface.

S9. Ans.(c)
Sol. We know that Z-transform of u(n) is 1/(1-z^(-1) ) with |z| > 1.

S10. Ans(b)
Sol. In Ex-OR logic gate if both the inputs are same then output is β€˜0’ otherwise output is β€˜1’ if both inputs are different or unlike.

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