RBSE Solutions for Class 11 Physics Chapter 1 Physical World

Rajasthan Board RBSE Solutions for Class 11 Physics Chapter 1 Physical World Textbook Exercise Questions and Answers.

RBSE Class 11 Physics Solutions Chapter 1 Physical World

RBSE Class 11 Physics Physical World Textbook Questions and Answers

Question 1.1.
Some of the most profound statements on the nature of science have come from Albert Einstein one of the greatest scientists of all, time. What do you think did Einstein mean when he said. “The most incomprehensible thing about the world is that it is comprehensible”?
Answer:
The physical world is highly complex. It has vast orders of magnitude in respect of mass, length and timer Even all the physical phenomena can be explained in terms of few basic principles of physics. That is, it is possible to comprehend nature in terms of few basic laws of its vast complexities. This is what Einstein meant to say.

Question 1.2.
“Every great physical theory starts as a heresy and ends as dogma.” Give some examples from the history of science of the validity of this incisive remark.
Answer:
Any opinion against the conventional belief is a heresy, while dogma is an stablisted belief. The geocentric theory of Copernicus started as a heresy but it ended as dogma when this theory was explained by Tycho Brahe and Johnes Kepler later on.

Question 1.3.
“Politics is an art of the possible.” Similarly “Science is the art of soluble”. Explain this beautiful aphorism on the nature and practice of Science.
Answer:
Politics talks only about the possibilities of solutions to problems which are faced by the world. But Sciehce offers solutions to the problems by way of inventions and discoveries. Think of advances in medicine, agriculture, engineering and other fields should have many of our pressing problems. Science is always at work to alleviate human suffering and to improve the quality of life.

Question 1.4.
Though India now has a large base in science and technology. Which is fast expanding, it is still a long way from realizing its potential of becoming a world leader in science. Name some important factors which in your view have hindered the advancement of Science in India. 
Answer:
No doubt, there is wide base of Science and technology in India, which is spreading repidly. But due to following reasons India cannot become lader in world.

1. Financial constraints: Due to financial constraints scientist cannot conduct research work freely.
2. Lack of understanding between scientists and industrialists.

Question 1.5.
No physicist has ever ‘seen’ an electron. Yet, all physicists believe in the existence of electron. An intelligent but superstitious man advances this analogy to argue that ‘ghosts’ exist even though no one has ‘seen’ one. How will you refuse his argument?
Answer:
No physicist has ever seen an electron. This is true. But there is so much of evidence that establishes the existence of electrons. On the contrary, there is hardly any evidence, direct or indirect to establish the existence of ghosts.

Question 1.6.
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 scientific explanation?
(a) A tragic sea accident several centuries ago drowned a young Samurai. As a tribute to his bravery, nature through its inscrutable ways immortalized his face by imprinting it on the crab shells in that area.
(b) 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 accidently 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’ high lights the fact that ofien strange an 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:
Explanation (b) is scientific explanation of the observed fact.

Question 1.7.
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:
Industrial revolution in England and Western Europe in 175 A.D. was triggered by some key scientific and technological advances. Development of ‘steam engine’, ‘blast furnace’ (which converts low grade iron into steel) and ‘cotton gin’ (which separate the seeds from cotton three hundred times faster than by hand) and ‘power loom’ are some of the examples.

Question 1.8.
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:
Some of the contemporary areas of Science and technology which may transform the society radically are:

1. Development of superconducting materials at room temperature.
2. Development of super fast computers.
3. Information explosion and advances in information technology.
4. Development in biotechnology.
5. Development of robots.

Question 1.9.
Write in about 100 words a fiction piece based on your speculation on the Science and technology of the twenty-second century.
Answer:
Imagine a spaceship heading towards a star about 100 light years away. It is propelled by electric current generated by electromagnetic induction, as the spaceship crosses the magnetic fields in space. The current is given to an electric motor made of super conducting wires. Thus, no energy would be required to propagate the spaceship over its entire journey. In a particular region of the space, suppose the temperature becomes so high that the super conducting property of the wires of the motor is destroyed. This causes a panic in the spaceship because no power is generated by the motor. In a split second, another space ship filled with matter and antimatter stored in different components to produce energy for the first ship comes to its rescue. Thus the first ship continues its onward journey.

Question 1.10.
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:
Science is the search for eternal truth. It is the moral duty of a scientist to expose the truth. If there is any danger to the mankind from a discovery, he should try to build a public opinion against the misuse of discovery. Moreover, he should develop the means to prevent its misuse. It is equally possible that this discovery may prove to be of emm'ense important to the mankind later on.

Question 1.11.
Science, like any knowledge, can be put to good or bad use, depending on the user. Given below are some of the applications of Science. Formulate your views on whether the particular application is good, bad or something that can not be so clearly categorized.
(a) Mass vaccination against small pox to curb and finally eradicate this disease from the population. (This has already been successfully done in India).
(b) Television for eradication of illiteracy and for mass communication of news and ideas.
(c) Prenatal sex determination.
(d) Computers for increase in work efficiency.
(e) Putting artificial satellites into orbits around the Earth.
(f) Development of nuclear weapons.
(g) Development of new and powerful techniques of chemical and biological warfare.
(h) Purification of water for drinking.
(i) Plastic surgery.
(j) Cloning.
Answer:
(a) Mass vaccination is good.
(b) Television for eradication of illiteracy for mass communication of news and ideas is really good. 
(c) Prenatal sex determination is not bad, but people are misusing it. They must be educated to avoid its misuse in creating inblance between male and female population.
(d) Computers for increase in work efficiency are good.
(e) Launching of artificial satellites into, orbits around the Earth is a good development.
(f) Nuclear weapons are mass destructive, therefore their development is bad.
(g) Development of new and powerful techniques of chemical and biological warfare is realy bad because these warfroms are meant for destruction of mankind.
(h) Purification of water for drinking purpose very good.
(i) Plastic surgery is good.
(j) Cloning is also good.

Question 1.12.
India has had a long and unbroken tradition of great scholarship in Mathematics, Astronomy, Linguistics, Logic and Ethics. Yet, in parallel with this, several superstitious and obscurantistic attitudes and practices flourished in our society and unfortunately continue even today among many educated people too. How will you use your knowledge of Science to develop strategies to counter these attitudes?
Answer:
Educating the common man is the only way to get rid of superstitions and obscurantist attitudes and practice flourished in our society. The phenomenon which people attribute to evil spirits and gods should be explained scientifically through mass media such as radio, television, news paper, cinema etc. The school students must be explained the day today phenomenon occuring around them in an effective scientific manner.

Question 1.13.
Though the law gives women equal status in India, many people hold unscientific views on a woman’s innate nature, capacity and intelligence, and in practice give them a secondary status and role. Demolish this view using scientific arguments, and by quoting examples of great women in Science and other spheres and persuade yourself and others that given equal opportunity, women are on par with men. 
Answer:
Development of human mind depends basically on nutrition content of prenatal and postnatal diet, and also on the care and use of the mind. There is no gender bias involved. Anything which can be achieved by man’s mind. Madam Curie won Nobel Prize in Physics. Mother Teresa proved herself saint. In politics, Mrs. Indira Gandhi; Mrs Margaret Thatcher, Mrs Bhandarnike excelled others.

Question 1.14.
“It is more important to have beauty in the equations of Physics then to have them agree with experiments”. The great British physicist P.A.M. Dirac held this view. Criticize this statement. Look out for some equations and results in this book which strike you as beautiful.
Answer:
A physical equation must be simple and hence beautiful. It will automatically agree with the experimental results. For example, consider Einstein’s mass energy equivalence E = mc². This simple equation not only governs energy generation in the sun and the other stars but it is also mainly responsible for energy generation on the earth from the process of nuclear fission and nuclear fusion. However, it is not always true. Although some equations of Quantum mechanics and theory of relativity are highly cumbersome and difficult to understand, yet they agree with the experiments.

Question 1.15.
Though the statement quoted above may be disputed, most physicists do have a feeling that the great laws of Physics are at once simple and beautiful. Some of the notable physicists, besides Dirac, who have articulated this feeling are: Einstein, Bohr, Heisenberg, Chandra Shekhar and Feynman. You are urged to make special efforts to get access to the general books and writings by these and other great masters of Physics. (See the Bibliography at the end of this book). Their writings are truly inspiring.
Answer:
General books on Physics make an interesting reading. Students are advised to consult good library. ‘Surely, you are joking, Mr. Feynman’ by Feynman is one of the books that would amuse the students. Some other interesting books are: Physics for the Inguiring Mind by E.M. Rogers; Physics, Foundations and Frontiers by G. Gamow; Thirly years that Shook Physics by G. Gamow; Physics Can be Fun by Perelman.

Question 1.16.
Textbooks on science may give you a wrong impression that studying science is dry and all too serious and Scientists are absent minded introverts who never laugh or grin. This image of Science and scientists is patently false. Scientists, like any other group of humans, have their share of humorists and many have led their lives with a great sense of fun and adventure, even as they seriously pursused their scientific work. Two great physicists of this genre are Gamow and Feynman. You will enjoy reading their books listed in the Bibliography.
Answer:
True, the scientists like any other group of humans have their share of humorists, and many have led their lives with great sense of fun and adventure inspite of pursuing their scientific work seriously. Two such great physicist were Gamow and Feynman.