Class 11 Physics

Physical World

Exercise

Part 2

Questions 5: No physicist has ever “seen” an electron. Yet, all physicists believe in the existence of electrons. An intelligent but superstitious man advances this analogy to argue that ‘ghosts’ exist even though no one has ‘seen’ one. How will you refute his argument?

Answer: It is true that no physicist has ever seen an electron. But many phenomena can explained with the help of theories on electrons. Scientists have also invented many useful devices by utilizing the properties of electrons. It is not true for ghost. We cannot explain any phenomenon on the basis of a ghost. We have yet to make a useful application from ghosts. So, there is every reason to believe the existence of electrons rather than the existence of ghost.

Questions 6: The shells of crabs found around a particular coastal location in Japan seem mostly to resemble the legendary face of a Samurai. Given below are two explanations of this observed fact. Which of these strikes you as a scientific explanation?

  1. A tragic sea accident several centuries ago drowned a young Samurai. As a tribute to his bravery, nature through its inscrutable ways immortalised his face by imprinting it on the crab shells in that area.
  2. After the sea tragedy, fishermen in that area, in a gesture of honour to their dead hero, let free any crab shell caught by them which accidentally had a shape resembling the face of a Samurai. Consequently, the particular shape of the crab shell survived longer and therefore in course of time the shape was genetically propagated. This is an example of evolution by artificial selection.

[Note: This interesting illustration taken from Carl Sagan’s ‘The Cosmos’ highlights the fact that often strange and inexplicable facts which on the first sight appear ‘supernatural’ actually turn out to have simple scientific explanations. Try to think out other examples of this kind].

Answer: Option (b)

Questions 7: The industrial revolution in England and Western Europe more than two centuries ago was triggered by some key scientific and technological advances. What were these advances?

Answer: Following were some key scientific and technological advances which catalysed the industrial revolution in England and Western Europe:

Questions 8: It is often said that the world is witnessing now a second industrial revolution, which will transform the society as radically as did the first. List some key contemporary areas of science and technology, which are responsible for this revolution.

Answer: Following are the key contemporary areas of science and technology which are facilitating the second industrial revolution:

Questions 9: Write in about 1000 words a fiction piece based on your speculation on the science and technology of the twenty-second century.

Answer: You can read Time Machine and Around The World in Eighty Days to take inspiration

Questions 10: Attempt to formulate your ‘moral’ views on the practice of science. Imagine yourself stumbling upon a discovery, which has great academic interest but is certain to have nothing but dangerous consequences for the human society. How, if at all, will you resolve your dilemma?

Answer: It is difficult to tell if a scientific discovery is going to prove harmful only. It depends on the way we use a particular innovation. For example; nuclear power can be used for making nuclear bombs as well as for producing electricity. Instead of blaming it on science we should think of the way we are going to use a particular innovation. If a particular innovation can be potentially dangerous than the world leaders and scientists devise proper checks and balances to prevent its misuse. Ultimately, the aim of a scientific discovery is to discover the truth.