*Mudra* Physical Sciences For NET & SET Exams. Of UGC-CSIR

_____________________________________________________________________________ (MCQs) Part B & C Vol-04

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MUDRA PHYSICAL SCIENCES

VOLUME-04

PART B & C

MODEL QUESTION BANK FOR THE TOPICS:

6. Electronics

UNIT-I 1

UNIT-II 15

UNIT-III 31

UNIT-IV 43

UNIT- V 93

*Mudra* Physical Sciences For NET & SET Exams. Of UGC-CSIR

_____________________________________________________________________________ (MCQs) Part B & C Vol-04

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6. ElectronicsUNIT-I

1. The depletion region is created bya) Ionization b) Diffusion c) Recombination d) All of these

2. A diode that has a negative resistance characteristic is the a) Schottky diode b) Tunnel diodec) Laser diode d) Hot-carrier cathode

3. A fine tungsten wire is used in: a) Geiger-Muller counter b) Proportional counter c) Wilson-cloud chambers d) Solid state detectors

4. The pulse height is constant over a range of applied voltages in: a) Wilson Cloud chamber b) Geiger Muller counter c) Proportional counter d) Solid-State detectors

5. The rate of deposition of positive charges in an ionization chamber is measured by: a) Quadrant electrometer b) Voltmeter c) Ammeter d) None of these

6. In a silicon P-N junction diode, a forward voltage of 0.1V is applied, the current that flows through a device is a few

a) Amperes b) Milli-amperesc) Pico-amperes d) Zero

7. If a sinusoidal voltage is applied to the base of a biased npn transistor and the resulting sinusoidal collector voltage is clipped near zero volts, the transistor is

a) Being driven into saturation b) Being driven into cutoffc) Operating non-linearly d) Both (a) and (c)

8. The internal resistance of a photodiodea) Increases with light intensity when reverse-biasedb) Decreases with light intensity when reverse-biasedc) Increases with light intensity when forward-biasedd) Decreases with light intensity when forward-biased

9. Law of intermediate metals in thermocouples allows them to: a) Use extension wires of materials other than the one used for making other than the

one used for making thermocouplesb) Use meters for measurement without disturbing the circuit condition c) Use reference function compensation d) Both (a) and (b)

*Mudra* Physical Sciences For NET & SET Exams. Of UGC-CSIR

_____________________________________________________________________________ (MCQs) Part B & C Vol-04

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10. The Knudsen gauge can over a range of pressure from: a) 610 to 110 Torr b) 910 to 410 Torrc) 810 to 210 Torr d) 1210 to 110 Torr

11. Radiation pyrometers are used in the temperature range of: a) 500 – 10000C b) 0 – 5000Cc) –250 – 5000C d) 1200 – 25000C

12. Which device led to the discovery of many elementary particles like meson, positron, etc?a) Bubble chamber b) Solid-State detectors c) Wilson-Cloud chamber d) X-ray diffraction

13. A 0.300V voltmeter has an error of %2 of full scale deflection. What would be the range of reading if true voltage is 30V?

a) 20 V to 40 V b) 24 V – 36 Vc) 29.4 V – 30.6 V d) None of these

14. A wattmeter has a full scale range of 2500 W. It has an error %1 of true value. What would be the range of reading if true power is 1250W?

a) 1245 W – 1255 W b) 1225 W – 1275 Wc) 1200 W – 1300 W d) 1237.5 W – 1262.5 W

15. A ferromagnetic core if placed inside a coila) Will decrease the coil inductance b) Will raise the resistance of the coilc) Will lower the resistance of the coil d) Will increase the coil inductance

16. The mean deviation d in terms of deviation from the mean value of n readings is:

a) n

db)

n

d

c) n

d 2 d) n

d 2

17. An ideal switch is one which has a) Zero resistance when ON or infinite resistance when OFF b) Zero resistance when OFF or infinite resistance when ON c) Zero resistance when ON or also zero resistance when OFF d) Non-zero but identical resistance when OFF or ON

18. If the result of a measurement is expressed as ;3X where X mean value and standard deviations, it means that:

a) 26 readings out of 1,000 will lie outside 3 limitb) Approximately 99 percent of the readings lie between 3 limitc) The odds for any reading to lie within 3 limit are 256 to 1d) All of the above

*Mudra* Physical Sciences For NET & SET Exams. Of UGC-CSIR

_____________________________________________________________________________ (MCQs) Part B & C Vol-04

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19. The time base of CRO is developed bya) Sawtooth waveform b) Square waveformc) Triangular waveform d) Sinusoidal waveform

20. A better power supply should possessa) Higher input impedance b) Lower output impedancec) Lower input impedance d) Total voltage regulation

21. The instrument employed for measuring very low resistance is: a) Meter bridge b) Carey-Foster’s bridgec) Kelvin’s double bridge d) Capacitor discharge

22. The luminous sensitivity of gas filled photoelectric cells varies between: a) 40 – 150 μA/1m b) 10 – 100 μA/1mc) 0.01 to 0.15 μA/μW d) 0.002 – 0.1 A/ μW

23. In a Wein-bridge oscillator, if the resistances in the positive feedback circuit are decreased, the frequency

a) Decreases b) Increases c) Remains the same d) Becomes zero

24. A JFET always operates witha) The gate-to-source pn junction reversed biasedb) The gate-to-source pn junction forward biasedc) The drain connected to ground d) The gate connected to the source

25. The sensitivity of a photovoltaic cell: a) Decreases with increase of load resistance b) Is almost constant when it is short circuited c) Is almost negligible when the load resistance is about 10000Ωd) All of the above

26. In a circuit maximum power transfer from source to load takes place whena) Load resistance is equal to source resistanceb) Load resistance is greater than source resistancec) Load resistance is less than source resistanced) None of the conditions hold

27. Photodiodes: a) Have a response even in darkness b) Do not have any response in darkness c) Have a leakage current even in darkness which is called dark current that doubles for

every 100C increase in the ambient temperature that decreases the signal to noise ratio d) Have a leakage current even in darkness which is called dark current that double for

every increases of 50C in temperature and which increases the signal for noise ratio

*Mudra* Physical Sciences For NET & SET Exams. Of UGC-CSIR

_____________________________________________________________________________ (MCQs) Part B & C Vol-04

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28. The main feature of a crystal oscillation is a) Economy b) Reliabilityc) Stability d) High frequency

29. The appropriate detector for fast MeV neutrons is: a) BF3 proportional counter b) Plastic scintillator c) GM counter d) Semiconductor detector

30. The resistance of a thermometer is 5Ω at 300C and 6.5Ω at 600C. Using linear approximation, the value of resistance temperature coefficient at 450C:

a) 0.0085/0C b) 0.0087/0Cc) 0.09/0C d) 0.01/0C

31. The gauge factor is defined as: (where L, D, P and R are respectively length, diameter, resistivity and resistance of strain gauge.

a) LL

RR

/

/

b) DD

RR

/

/

c) PP

RR

/

/

d) RR

LL

/

/

32. Magnetizing force is measured by Nuclear Magnetic Resonance method. The expression for magnetizing force is:

a) FlhH 2 b) FlhvH c) 4/fhH d) flv2

33. In a FET a) Both the functions are reversed biasedb) One function is reversed biased and the other forward biasedc) One function has reversed biased on both side of the functiond) One function has reversed biased on other side and forward biased on the other side

34. A wheatstone’s bridge is being used to measure as unknown resistance X by adjusting the variable resistance Y. Accurate measurement of X is made only when:

π

P

Y X

Q

a) P and Q are very largeb) P and Q are equal but they have very small values c) Value of P and Q do not matter since it is a null measurement d) P and Q are about equal and of the same order as X

*Mudra* Physical Sciences For NET & SET Exams. Of UGC-CSIR

_____________________________________________________________________________ (MCQs) Part B & C Vol-04

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35. Each R-C network in the phase shift oscillator introduces a phase change of a) 180 b) 360c) 90 d) 60

36. A bipolar junction transistor with one junction forward biased and either the collector or emitter open, operates in the

a) Cut-off region b) Saturation region c) Pinch off region d) Active region

37. The spring for producing controlling torque in measuring instrument is made of: a) Phosphor bronze b) Platinum iridium c) Copper d) Aluminium

38. What is the energy of a neutron in relation with de-Broglie wavelength λ?

a) nM

h

2

2

b) 2

2

4 nM

h

c) 2

2

2 nM

hd) 0

39. The source of emission of electrons in a CRT is: a) A barium and strontium oxide coated cathodeb) P-N junction diode c) Accelerating anode d) Post-accelerating anode

40. The operation of a relaxation oscillator is based on a) The charging and discharging of a capacitorb) A highly selective resonant circuitc) A very stable supply voltaged) Low power consumption

41. In a wheatstone’s bridge the sensitivity is maximum when:

P

R S

Q

G

B

a) P, Q, R, S are all small order b) P, R are large, Q, S are small c) P, Q, are large R, S are small d) Q, S are large, P, R are small

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