General Science - Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examinations.
91. Which of the following is correct?
[A] Freely suspended magnet always align in north-south direction
[B] Magnetic poles of a magnet are of equal strength
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: C [Both a and b]
Notes:
A freely suspended magnet always align in north-south direction. The magnetic poles of a magnet are of equal strength and always exist in pairs.
92. What is the susceptibility of a diamagnetic material?
[A] positive and small
[B] positive and large
[C] negative
[D] None
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Correct Answer: C [negative]
Notes:
In terms of the susceptibility χ , a material is diamagnetic if χ is negative, para- if χ is positive and= small, and ferro- if χ is large and positive
93. What do we call the atomic species of the same element differing in mass?
[A] Isobars
[B] Isotopes
[C] Isomers
[D] Such species don’t exist
Show Answer
Correct Answer: B [Isotopes]
Notes:
The atomic species of the same element differing in mass are called isotopes.
94. Which of these rays have the highest ionising power?
[A] Alpha
[B] Beta
[C] Gamma
[D] All have the same
Show Answer
Correct Answer: A [Alpha]
Notes:
Alpha rays have the highest ionising power followed by Beta rays and then Gamma rays.
95. When is a p-n diode said to be forward biased?
[A] when p-side is connected to the positive terminal of the battery
[B] when n-side is connected to the positive terminal of the battery
[C] when p-side is connected to the negative terminal of the battery
[D] None of the above
Show Answer
Correct Answer: A [when p-side is connected to the positive terminal of the battery]
Notes:
When an external voltage V is applied across a semiconductor diode such that p-side is connected to the positive terminal of the battery and n- side to the negative terminal.
96. What is a p-n diode said to be in reverse-bias?
[A] positive terminal of the external battery is connected to the p-side
[B] positive terminal of the external battery is connected to the n-side
[C] negative terminal of the external battery is connected to the n-side
[D] None of the above
Show Answer
Correct Answer: B [positive terminal of the external battery is connected to the n-side]
Notes:
If the positive terminal of the external battery is connected to the n-side and the negative terminal of the external battery is connected to the p- side, then the p-n junction is said to be reverse biased.
97. Which of the following is NOT the criteria for material selection for a solar cell?
[A] It should be cost effective
[B] It should have a band gap between 1.0 and 1.7 eV
[C] It should have low absorption coefficient
[D] All of the above
Show Answer
Correct Answer: C [It should have low absorption coefficient]
Notes:
It should have high optical absorption. In a material with a low absorption coefficient, light is only poorly absorbed.
98. What happens to the resistance of a p-n junction diode when forward biased?
[A] it becomes high
[B] No effect
[C] it becomes low
[D] it becomes zero
Show Answer
Correct Answer: C [it becomes low]
Notes:
The resistance of a p-n junction diode becomes low when forward biased and becomes high when reverse biased. This is the principle of the working of rectifier.
99. What is the output of an AND gate when both the inputs are 0?
[A] 0
[B] 1
[C] Either 0 or 1
[D] 2
Show Answer
Correct Answer: A [0]
Notes:
The AND gate is a basic digital logic gate that gives a LOW output If none or not all inputs to the AND gate are HIGH.
100. What is the charge of a p-type semiconductor?
[A] Positive
[B] Negative
[C] Neutral
[D] None of the above
Show Answer
Correct Answer: C [Neutral]
Notes:
The number of free electrons is exactly equal to the total number of holes and positively charged ions and a semiconductor, whether intrinsic or doped, is electrically neutral
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