Quiz Electronics Engineering 7 Sep 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 07/09/2020

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

Q1. A unit impulse function 𝛿(t) is defined by
1. 𝛿(t) = 0 for all t except t = 0
2. ∫_(-∞)^∞▒〖δ(t)〗dt = 1
The Fourier Transform F(ω) of 𝛿(t) is
(a) 1
(b) 1/ω
(c) 0
(d) 1/jω

Q2. The electrical systems which operate at two discrete voltage levels is knows as ……… system.
(a) hybrid
(b) digital
(c) analog
(d) none of the above.

Q3. The number of valence electrons in pentavalent impurity is:
(a) 3
(b) 4
(c) 5
(d) 1

Q4. The synchronization between microprocessor and memory is done by –
(a) READY signal
(b) ALE signal
(c) HOLD signal
(d) None of the above

Q5. When the phase velocity of an electromagnetic wave depends on frequency in any medium, the phenomenon is called
(a) Scattering
(b) polarization
(c) absorption
(d) dispersion

Q6. In a PCM system with uniform quantization, increasing the number of bits from 8 to 9 will reduce the quantization noise power by a factor of
(a) 9
(b) 8
(c) 4
(d) 2

Q7. What is loopback address ?
(a) 127.0.0.1
(b) 255.0.0.0
(c) 255.255.0.0
(d) 127.0.0.0

Q8. An input/output device at which data enters or leaves a computer system is:
(a) keyboard
(b) plotter
(c) printer
(d) terminal

Q9. Due to which of the following reasons a NAND gate is called a Universal logic element?
(a) Many digital computers use NAND gates
(b) All the minimizing techniques are applicable for optimum NAND gate realization
(c) Any logic function can be realized by NAND gate alone
(d) All of the above

Q10. For Half-wave(odd) symmetry, with T_o = period of x(t), which one of the following is correct?
(a) x(t ± T_o/2) = -x(t)
(b) x(t ± T_o/2) = -x(t)
(c) x(t ± T_o) = -x(t)
(d) x(t ± T_o) = x(t)

SOLUTIONS

S1. Ans.(a)
Sol. Fourier Transform is –
𝛿(t) □(↔┴( F.T ) ) 1

S2. Ans.(b)
Sol. The electrical systems which operate at two discrete voltage levels either at High Voltage level or Low Voltage level is known as Digital System.

S3. Ans. (c)
Sol. Valence electron are electrons located in the outermost shell of an atom.

S4. Ans.(a)
Sol. READY signal is used to interface with the slower peripheral devices(Memory or I/O devices) to the microprocessor.

S5. Ans.(b)

S6. Ans.(c)
Sol. We know that, Quantization noise in PCM is given by
⇒ NQ = Δ^2/12
where,
Δ = (Dynamic range)/L = V_(P-P )/2^n
Now,
NQ = V_(P-P)^212 x 22n
⇒ N_Q ∝ ( 1)/( 2^2n )
For n = 8,
⇒ 〖N_Q〗_1 ∝ ( 1)/( 2^(2 x 8) ) = ( 1)/( 2^16 )
For n = 9,
⇒ 〖N_Q〗_2 ∝ ( 1)/( 2^(2 x 9) ) = ( 1)/( 2^18 )
and (〖N_Q〗_2 )/(〖N_Q〗_1 ) = (( 1)/( 2^18 ))/(( 1)/( 2^16 )) = 2^16/2^18 = 1/4
So, 〖N_Q〗_2 = (〖N_Q〗_1 )/4

S7. Ans.(a)
Sol. 127.0.0.1 is the loopback IP address. It is used to test the communication or transportation medium on a local network card or for testing network applications. Data packets sent on a loopback address are re-routed back to the originating node without any alteration or modification. It is a communication channel with only one endpoint. TCP/IP networks specify a loopback that allows client software to communicate with server software on the same computer.

S8. Ans.(c)

S9. Ans.(b)
Sol. A NAND gate is called a Universal logic element because all the minimizing techniques are applicable for optimum NAND gate realization. We can implement any logic circuit using the NAND gate.

S10. Ans.(a)
Sol. For Odd half-wave symmetry –
x(t) = -x(t±T_o/2)

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