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5 questions · 2013 · answers as per the UPSC key

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UPSC 2013 · Q88 · Science & Technology › Physics · Save

Ball bearings are used in bicycles, cars, etc., because

(a) the actual area of contact between the wheel and axle is increased
(b) the effective area of contact between the wheel and axle is increased
(c) the effective area of contact between the wheel and axle is reduced
(d) None of the above statements is correct
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Answer: (c) the effective area of contact between the wheel and axle is reduced
UPSC 2013 · Q89 · Science & Technology › Physics · Save

Consider the following phenomena:

  1. Size of the sun at dusk
  2. Colour of the sun at dawn
  3. Moon being visible at dawn
  4. Twinkle of stars in the sky
  5. Polestar being visible in the sky

Which of the above are optical illusions?

(a) 1, 2 and 3
(b) 3, 4 and 5
(c) 1, 2 and 4
(d) 2, 3 and 5
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Answer: (c) 1, 2 and 4
UPSC 2013 · Q90 · Science & Technology › Physics · Save

Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this?

  1. Dispersion
  2. Refraction
  3. Internal reflection

Select the correct answer using the codes given below.

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
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Answer: (d) 1, 2 and 3
UPSC 2013 · Q95 · Science & Technology › Physics · Save

The known forces of nature can be divided into four classes, viz., gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?

(a) Gravity is the strongest of the four
(b) Electromagnetism acts only on particles with an electric charge
(c) Weak nuclear force causes radioactivity
(d) Strong nuclear force holds protons and neutrons inside the nucleus of an atom
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Answer: (a) Gravity is the strongest of the four
UPSC 2013 · Q96 · Science & Technology › Physics · Save

The efforts to detect the existence of Higgs boson particle have become frequent news in the recent past. What is/are the importance/ importances of discovering this particle?

  1. It will enable us to understand as to why elementary particles have mass.
  2. It will enable us in the near future to develop the technology of transferring matter from one point to another without traversing the physical space between them.
  3. It will enable us to create better fuels for nuclear fission.

Select the correct answer using the codes given below.

(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
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Answer: (a) 1 only