General Science - Physics
Welcome to General Science – Physics MCQ series of GKToday. As of today February 26, 2020, this series has 590 Questions. You may purchase a PDF E-Book compilation comprising all these questions and their answers with explanation from this link.
91. Which of these are called as Universal logic gates?
[A] NAND
[B] NOR
[C] NOT
[D] Both a and b
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Correct Answer: D [Both a and b]
Notes:
The NAND gate and the NOR gate are called as universal gates as any Boolean function can be implemented without the need to use any other gate.
92. Which of the following diodes is mostly commonly used as a voltage regulator?
[A] LED
[B] Varactor diode
[C] Shockley diode
[D] Zener diode
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Correct Answer: D [Zener diode]
Notes:
Zener diode is a special purpose semiconductor diode, named after its inventor C. Zener. It is designed to operate under reverse bias in the breakdown region and used as a voltage regulator.
93. Which of these diodes is used to detect optical signals?
[A] Photodiode
[B] Light emitting diode
[C] Photovoltaic diode
[D] None of the above
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Correct Answer: A [Photodiode]
Notes:
Photodiode can be used as a photodetector to detect optical signals.
94. Which of these diodes convert electrical energy into light?
[A] Photodiodes
[B] Light emitting diodes
[C] Photovoltaic devices
[D] None
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Correct Answer: B [Light emitting diodes]
Notes:
Light emitting diodes (LED) are special diodes which convert electrical energy into light.
95. Which type of semiconductor do we get when pure silicon is doped with a group-5 element?
[A] n-type semiconductor
[B] p-type semiconductor
[C] Intrinsic semiconductor
[D] None of the above
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Correct Answer: A [n-type semiconductor]
Notes:
The semiconductor doped with pentavalent impurity, electrons become the majority carriers and holes the minority carriers. These semiconductors are, therefore, known as n-type semiconductors.
96. Which type of semiconductor do we get when pure silicon is doped with a group-3 element?
[A] n-type semiconductor
[B] p-type semiconductor
[C] Intrinsic semiconductor
[D] None
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Correct Answer: B [p-type semiconductor]
Notes:
If silicon (or germanium) is doped with a trivalent (three electrons in the outermost shell) atom like boron, aluminium, gallium or indium, three valence electrons form covalent bonds with three silicon atoms and deficiency of one electron is created. Such a semiconductor is said to be a p- type semiconductor.
97. Which of these is an acceptor impurity?
[A] Phosphorus
[B] Arsenic
[C] Antimony
[D] Indium
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Correct Answer: D [Indium]
98. Which of the following is correct about conductors?
[A] The conduction band and the valence band partly overlap each other
[B] There is no forbidden energy band gap between conduction band and the valence band
[C] Both a and b
[D] None of the above
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Correct Answer: C [Both a and b]
Notes:
The conduction band and the valence band partly overlap each other and there is no forbidden energy band gap in between. The electrons from the valence band can easily move into the conduction band. Hence, large number of electrons are available for conduction.
99. Which of these is known as God particle?
[A] Mesons
[B] Electrons
[C] Higgs boson
[D] Neutrinos
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Correct Answer: C [Higgs boson]
Notes:
Higgs boson are also known by its nickname the “God particle”.
100. Who invented Nuclear Reactor?
[A] James Watt
[B] Otto Hahn
[C] Michael Faraday
[D] Enrico Fermi
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Correct Answer: D [Enrico Fermi]
Notes:
Enrico Fermi invented the first Nuclear reactor.
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