UPSC Prelims Practice Questions — The Science QUIZ
Q1. In the context of spaceflight, the 'gravity-assist' (gravitational slingshot) technique is best defined as which one of the following?
- A. A manoeuvre in which a spacecraft uses a planet's gravitational field to exchange momentum with the planet, thereby altering the spacecraft's speed and trajectory without expending propellant
- B. A manoeuvre in which a spacecraft fires its main engine at closest approach to a planet so as to maximise the fuel efficiency of the burn
- C. A method by which a spacecraft is captured into a stable orbit around a planet using that planet's gravity alone
- D. A manoeuvre in which a spacecraft's speed relative to the planet it flies past is permanently increased after the encounter
Q2. Which one of the following was the first spacecraft ever to use a planetary gravity assist?
- A. Mariner 10
- B. Voyager 1
- C. Cassini
- D. BepiColombo
Q3. Which one of the following is the outermost region of a rotating (Kerr) black hole from within which the Penrose process can extract rotational energy?
- A. The ergosphere
- B. The event horizon
- C. The photon sphere
- D. The central singularity
Q4. The theoretical mechanism for extracting rotational energy from a spinning black hole — the 'Penrose process' — was first proposed in 1969 by which one of the following scientists?
- A. Roger Penrose
- B. Stephen Hawking
- C. Reinhard Genzel
- D. Andrea Ghez
Q5. Which one of the following is credited with operating, in 1959, the first truly successful magnetohydrodynamic (MHD) power generator?
- A. Richard J. Rosa
- B. Bela Karlovitz
- C. Humphry Davy
- D. Michael Faraday
Q6. With reference to magnetohydrodynamic (MHD) power generation compared with conventional thermal power generation, consider the following statements:
1. An MHD generator produces electricity by passing an electrically conducting gas through a magnetic field, in accordance with Faraday's law of induction.
2. The potential ultimate efficiency of an MHD-based system (about 60–65%) is higher than the 35–40% typically achieved by a modern conventional thermal plant.
3. In an MHD generator, the induced electric field acts parallel to the direction of the gas flow.
Which of the statements given above is/are correct?
- An MHD generator produces electricity by passing an electrically conducting gas through a magnetic field, in accordance with Faraday's law of induction.
- The potential ultimate efficiency of an MHD-based system (about 60–65%) is higher than the 35–40% typically achieved by a modern conventional thermal plant.
- In an MHD generator, the induced electric field acts parallel to the direction of the gas flow.
- A. 1 and 2 only
- B. 1 and 3 only
- C. 2 and 3 only
- D. 1, 2 and 3
Q7. With reference to the Casimir effect, consider the following statements:
1. It was first postulated in 1948 by the Dutch physicist Hendrik Casimir.
2. It arises from the zero-point energy of the quantum vacuum's normal modes, present even in the absence of any external field.
3. A repulsive form of the Casimir effect was first experimentally observed in 2008 by Jeremy Munday and Federico Capasso.
4. The Casimir force is fundamentally a classical electrostatic attraction between electrically charged plates.
Which of the statements given above is/are correct?
- It was first postulated in 1948 by the Dutch physicist Hendrik Casimir.
- It arises from the zero-point energy of the quantum vacuum's normal modes, present even in the absence of any external field.
- A repulsive form of the Casimir effect was first experimentally observed in 2008 by Jeremy Munday and Federico Capasso.
- The Casimir force is fundamentally a classical electrostatic attraction between electrically charged plates.
- A. 1 and 4 only
- B. 2 and 3 only
- C. 1, 2 and 3 only
- D. 1, 2, 3 and 4
Q8. With reference to the Casimir effect, consider the following statements:
1. It can cause closely spaced parts of nanomachines to stick together.
2. In its usual form it produces an attractive force between two uncharged parallel plates in a vacuum.
3. Its repulsive form was demonstrated using a gold-plated sphere and a silica plate immersed in bromobenzene.
4. The effect vanishes completely once all classical electromagnetic fields are removed from the space between the plates.
Which of the statements given above is/are NOT correct?
- It can cause closely spaced parts of nanomachines to stick together.
- In its usual form it produces an attractive force between two uncharged parallel plates in a vacuum.
- Its repulsive form was demonstrated using a gold-plated sphere and a silica plate immersed in bromobenzene.
- The effect vanishes completely once all classical electromagnetic fields are removed from the space between the plates.
- A. 1 only
- B. 3 only
- C. 4 only
- D. 2 and 4
Q9. According to estimates cited in recent research, approximately how much salinity-gradient (osmotic) power is available from the roughly 37,000 km³ of river water discharged into the oceans each year?
- A. About 0.2 TW
- B. About 2 TW
- C. About 20 TW
- D. About 200 TW
Q10. In which year was the concept of generating electric power by mixing fresh and salt water (salinity-gradient or 'blue' energy) first proposed, in a paper published in Nature by R.E. Pattle?
- A. 1948
- B. 1954
- C. 1969
- D. 1978