RITESLtd Technical-Electronics Contributed by Suraj updated on Jun 2019

                    RITES Ltd Solved Model Placement Paper - Electronics

1. In a mercury arc rectifier

a. Ion stream moves from cathode to anode
b. Current flows from cathode to anode
c. Electron stream moves form anode to cathode
d. Ion stream moves from anode to cathode

2. For producing cathode spot in a mercury arc rectifier
a. An auxiliary electrode is used
b. Tube is evacuated
c. Low mercury vapour pressures are used
d. Anode is heated

3. If the voltage of anode B is raised to 510 V
a. Anode B will conduct but anode A will also continue to conduct
b. Anode B will not conduct but anode A will continue to conduct
c. Both anodes will not conduct
d. None of these

4. Ripple frequency of full wave rectifier working on 50 Hz supply will be
a. 25 Hz
b. 150 Hz
c. 6 anode rectifier with inter phase transformer
d. All will have identical power factor

5. The form factor for half-wave rectifier sine wave is
a. 1.05
b. 1.15
c. 1.45
d. 1.57

6. A silicon controlled rectifier is a
a. Unijuction device
b. Device with three junctions
c. Device with four junctions
d. None of the above

7. For full-wave rectifier sine wave, form factor is
a. 1.55
b. 1.44
c. 1.22
d. 1.11

8. At absolute zero temperature a semi-conductor behaves as
a. An Insulator
b. A Super-Conductor
c. A Good Conductor
d. A Variable Resistor

9. An electron in the conduction band
a. Has higher energy than the electron in the valence band
b. Has lower energy than the electron in the valence band
c. Loses its charge easily
d. Jumps to the top of the crystal

10. EG for silicon is 1.12 eV and for germanium is 0.72 eV thus it can be conducted that
a. More number of electron-hole pairs will be generated in silicon than in germanium at room temperature
b. Less number of electron hole pairs will be generated in silicon than in germanium at room temperature
c. Equal number of electron hole pairs will be generated in both at lower temperatures
d. Equal number of electron hole pairs will be generated in both at higher temperatures

11. Before doping semiconductor material is generally
a. Dehydrated
b. Heated
c. Hardened
d. Purified

12. Select the one that is a acceptor impurity element
a. Antimony
b. Gallium
c. Arsenic
d. Phosphorous

13. At room temperature when a voltage is applied to an intrinsic semiconductor
a. Most of the electrons and holes move towards negative terminal
b. Most of the electrons and holes move towards positive terminal
c. Electrons move towards positive terminal and holes towards negative terminal
d. Electrons move towards negative terminal and holes towards positive terminal

14. Under which of the following conditions avalanche breakdown in a semiconductor diode takes place ?
a. When potential barrier is reduced to zero
b. When reverse bias exceeds a certain value
c. When forward bias exceeds a certain value
d. When forward current exceeds a certain value

15. Select the rectifier that needs four diodes
a. Half wave rectifier
b. Center-tap full wave rectifier
c. Bridge rectifier
d. None of the above

16. Maximum forward current in case of signal diode is in the range of
a. 1A to 10A
b. 0.1A to 1A
c. Few milli amperes
d. Few nano amperes

17. In a semiconductor avalanche breakdown takes place when
a. Reverse bias exceeds the limiting value
b.Forward bias exceeds the limiting value
c. Forward current exceeds the limiting value
d. Potential barrier is reduced to zero

18. The D.C output from a power supply
a. Increases with higher values of filter capacitance and decreases with more load current
b. Decreases with higher values of filter capacitance and increases with more load current
c. Decreases with higher values of filter capacitance as well as with more load current
d. Increases with higher values of filter capacitance as well as with more load current

19. A solar cell provides a example of
a. Photo Voltaic Cell
b. Photo Conductive Cell
c. Photo Emissive Cell
d. Photo Radiation Cell

20. When yellow light is incident on a surface, no electrons are emitted while green light can emit. If red light is incident on the surface, then it is expected that
a. No electrons are emitted
b. Hotons are emitted
c. Electrons of higher energy are emitted
d. Electrons of lower energy are emitted

21. An ideal diode should have
a. Zero resistance in the forward bias as well as reverse bias
b. Zero resistance in the forward bias and an infinitely large resistance in reverse bais
c. Infinitely large resistance in reverse bias
d. Infinitely large resistance in forward as well as reverse bais

22. The reverse resistance of a PN juction diode
a. Is always low
b. Is always high
c. Is given by breakdown voltage / reverse leakage current
d. Is given by forward voltage / reverse leakage current

23. In which case the temperature coefficient is positive
a. Intrinsic Semi-Conductor
b. Extrinsic Semi-Conductor
c. Both intrinsic as well as extrinsic semi-conductor
d. Neither intrinsic nor extrinsic semi-conductor

24. A PNP transistor is generally made of
a. Silicon
b. Germanium
c. Either silicon or germanium
d. None of the above

25. In a transistor the region that is very lightly doped and is very thin is
a. Emitter
b. Base
c. Collector
d. None of these

26. In a NPN transitor, when emitter junction is forward biased and collector junction is reverse biased, the transistor will operate in
a. Active Region
b. Saturated Region
c. Cut of Region
d. Inverted Region

27. A transistor will operate in inverted region if
a. Emitter junction is forward biased and collector junction is reverse biased
b. Emitter junction is reverse biased and collector junction is forward biased
c. Emitter junction as well as collector junction are forward biased
d. Emitter junction as well as collector junction are reverse biased

28. Which of the following is essential for transistor action ?
a. The base region must be very wide
b. The base region must be very narrow
c. The base region must be made of some insulating material
d. The collector region must be heavily doped

29. In a transistor, current ICBO flows when
a. Some D.C voltage is applied in the reverse direction to the emitter junction with the collector open circuited
b. Some D.C voltage is applied in the forward direction to the collector junction with the emitter open circuited
c. Some D.C voltage is applied in the reverse direction to the collector junction with the emitter open circuited
d. Some D.C voltage is applied in the forward direction to the emitter junction with the collector open circuited

30. The current Icbo
a. Increases with increase in temperature
b. Is normally greater for silicon transistors than germanium transistors
c. Mainly depends on the emitter base junction
d. Depends largely on the emitter doping

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