CPCB Scientist B Paper | Central Pollution Control Board Scientist B Old Paper for Electronics & Communication

(Every Correct answer 1 mark, every wrong answer – 0.25 mark as a negative marking)

In inductive circuit, when Inductance (L) or inductive reactance (XL) increases, the circuit current decreases, and the circuit power factor _______?
(a) increases
(b) also decreases
(c) Remain same
(d) None of the above

If current and voltage are 90 degree out of phase, then the power (P) will be ______
(a) Infinite
(b) Maximum
(c) Minimum
(d) Zero

Mobility of electron is
(a) Average flow of electrons per unit field
(b) Average applied field per unit drift velocity
(c) Average drift velocity per unit charge
(d) Reciprocal of conductivity per unit charge

For a small value of VDS the channel in MOSFET
(a) Is not formed
(b) is pinched
(c) Acts as linear resistor whose value is controlled by VGS
(d) Acts as linear resistor whose value is controlled by VDs

What is the range of the input impedance of a common-base configuration?
(a) Few ohms to a maximum of 50 Ohms
(b) 1 Ohm to 5 Ohms
(c) 100 k Ohm to 500 k Ohms
(d) 1 M Ohm to 2 M Ohms

An industry-standard file that lists which all “fuses” in the programmable logic device are intact and which are to be blown is called
(a) Block Definition File
(b) VHDL File
(c) JEDEC File
(d) Vector Waveform File

A term associated with the comparison of processing speeds of different computer system is
(a) EFTS
(b) MPG
(c) MIPS
(d) CFPS

The minimum time for which the input signal has to be maintained at the input of flip flop is called
(a) Set up time
(b) Hold time
(c) Pulse Interval time
(d) Pulse Stability time (PST)

A debouncing circuit is
(a) an astable multivibrator
(b) a bistable multivibrator
(c) a monostable multivibrator
(d) a latch

Which of the following is used as a data selector?
(a) Encoder
(b) Decoder
(c) Multiplexer
(d) Demultiplexer

A Johnson counter stores 1000 0000 the count value in next clock pulse will be
(a) 0000 0001
(b) 1100 0000
(c) 0100 0000
(d) 1111 1111

A drawback with the DAC architecture “R-2R” is
(a) glitches
(b) variable input resistance
(c) resistor matching
(d) linearity

An eight bit digital data 10101100 is fed to an ADC. The reference voltage is +10 V. The analog output voltage will be
(a) 1.05 V
(b) 6.53 V
(c) 10.10 V
(d) 11.11 V

What should be the oscillator frequency for tuning in 710 KHz on an AM radio with a 455 KHz IF?
(a) 1165 KHz
(b) 1015 KHz
(c) 255 KHz
(d) 127.5 KHz

What is the resolution of a digital-to-analog converter (DAC)?
(a) It is the comparison between the actual output of the converter and its expected out put
(b) It is the deviation between the ideal straight-line output and the actual output of the converter
(c) It is the smallest analog output change that can occur as a result of an increment in the digital input
(d) It is its ability to resolve between forward and reverse steps when sequenced over its entire range.