NCERT Solution (Class 11) > Physics Chapter 1 Physical World
NCERT Solution Class 11 Physics Chapter 1 Physical World: National Council of Educational Research and Training Class 11 Physics Chapter 1 Solution – Physical World. Free PDF Download facility available at our website.
Board |
NCERT |
Class |
11 |
Subject |
Physics |
Chapter |
1 |
Chapter Name |
Physical World |
Topic |
Exercise Solution |
Physical World Chapter all Questions and Numericals Solution
CHAPTER1-PHYSICAL WORLD
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-
INCOMPREHENSIBLE means impossible to understand. As the Physical world is having enormous complex phenomena which are very difficult to understand at first stage makes it incomprehensible But by observing physical environment carefully and looking for any meaningful patterns and relations in natural phenomena human lead to conclusion that all these phenomena are based on some natural physical laws and so we can say that physical world is comprehensible.
1.2) “Every great physical theory starts as a heresy and ends as a dogma”. Give some examples from the history of science of the validity of this incisive remark.
ANSWER-
There are many examples from the history of science to justify this statement. Some of the examples are stated below
- Famous scientist Avogadro proposed that equal volumes of different gases contain an equal number of molecules, provided that they are at same pressure and temperature. During his lifetime this hypothesis was rejected but later on after many years it was considered to be correct.
- Famous example is Huygens theory of light. According to newton’s corpuscular theory light is made up of tiny particles called corpuscles but Huygens came up with wave theory of light which states that light travels in the form of wave with speed of light. This was considered as a heresy initially but when this wave theory explains the phenomenon like reflection, refraction then it became a dogma.
- Initially it was considered that earth is stationary and sun is revolving around the earth later on aristarchus by his theory proposed that earth is revolving around the sun and sun is stationary, at that time this theory was heresy but after many years theory became dogma with the support of many theories from Nicholas Copernicus, Kepler, newton and many more.
1.3) “Politics is the art of the possible”. Similarly, “Science is the art of the soluble”. Explain this beautiful aphorism on the nature and practice of science.
ANSWER-
According to the statement “Politics is the art of the possible”, politicians have some preplanned strategy to win the elections and to fulfill this they can do whatever may be possible. Hence we can say Politics is the art of the possible.
Word soluble means something that is solvable. Science is having number of laws theories and to prove these laws and theories scientists can do whatever may be possible like politicians that is why Science is the art of the soluble similar to Politics is the art of the possible.
1.4 Though India now has a large base in science and technology, which is fast expanding, it is still a long way from realising 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-
Following factors have hindered the advancement of science in India.
- Lack of funding for research from government.
- Considerable percentage of uneducated population.
- Grade oriented education system and not knowledge oriented.
1.5) 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-
No physicist has ever “seen” an electron. Yet, all physicists believe in the existence of electrons because many experiments like cathode ray tube experiment, J.J. Thompson’s experiments , Rutherford’s experiments gave evidence that some negatively charged particles exist called electron. Many day to day life phenomenon like stability of atoms gives support to the theory of existence of electron on the other hand there is no any phenomenon which can be explained by considering ghost existence hence comparing these two things is stupid thing with no base at all.
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 a scientific explanation?
- 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.
- 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-
By observing explanation given in (a) it makes no sense that nature immortalised samurai face by imprinting it on the crab shells in that area. Hence explanation given in (b) is scientific explanation as it is about evolution of shape of crab shell which is scientifically acceptable.
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-
Some key scientific and technological advances like discovery of dynamos and motors, development of power looms which changes the textile industry, along with this steam engine discovery made revolution in transport system, development of furnace made steel from iron brought revolution in steel industry and development in chemistry and physics also helped in making the industrial revolution in England and Western Europe.
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 key contemporary areas of science and technology, which are responsible for this revolution.
- Advancement in artificial intelligence.
- Developments in semiconductor and super conductor materials.
- Development of super computers.
- Development in genetic engineering and biotechnology
- Development in internet.
- Development of robots.
1.9 Write in about 1000 words a fiction piece based on your speculation on the science and technology of the twenty-second century.
ANSWER-
As per the speed of growth of science we may see huge change in twenty-second century.
- With the development of strong and new materials humans can travel with the speed comparable to speed of light in space in spacecraft.
- Humans may settle on another habitual planet with the help of advancement in space technology.
- Many incurable diseases may be cured completely with advancement in genetic engineering and bioengineering.
- Many damaged body parts can be regenerated with the help of cell regeneration.
- With the help of artificial intelligence everyone at their home will have a robot to do day to day work like washing clothes, making breakfast and many more.
- In industry every work may be performed by robots and many critical surgeries may be performed by intelligent robots by themselves.
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-
A discovery, which has great academic interest, should be practiced even though it has dangerous consequences for the human society.in the long run it will be helpful for making any device or any product which may be helpful to society in any way. If we consider example of development of nuclear fusion and fission reactions. Nuclear bomb or hydrogen bomb is dangerous to human society but some applications like nuclear reactors based on these principles helps the society in many ways.
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 cannot be so clearly categorise:
(a) Mass vaccination against small pox to curb and finally eradicate this disease from the population.(This has already been successfully done in India).
ANSWER-good
(b) Television for eradication of illiteracy and for mass communication of news and ideas.
ANSWER- Good
(c) Prenatal sex determination
ANSWER- Bad because it may cause abortion by parents if child is unwanted female.
(d) Computers for increase in work efficiency
ANSWER-Good
(e) Putting artificial satellites into orbits around the Earth
ANSWER-Good
(f) Development of nuclear weapons
ANSWER- Bad because nuclear weapons may cause big damage to humans and nature earth.
(g) Development of new and powerful techniques of chemical and biological warfare).
ANSWER-Bad because these techniques of chemical and biological warfare may cause big damage to humans.
(h) Purification of water for drinking
ANSWER-Good
(i)Plastic surgery
ANSWER- Good or bad depending upon for which purpose it is used.
(j) Cloning
ANSWER-BAD
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 obscurantist 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-
Several superstitious and obscurantist attitudes and practices flourished in our society due to illiteracy. So major solution is to literate peoples so that peoples will have that scientific approach towards everything which will make them believe in science. Again we are having some educated peoples which are superstitious too so We can use our knowledge of science to give them real logic behind things with the help of shows on televisions or articles in newspaper and blogs and making informative videos with the logic etc.
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-
If equal opportunities are offered to men and women, women are on par with men because history proved this many times for example scientist Marie curie who done great research on radioactivity and having noble prize for physics as well as chemistry in her wardrobe. Other women like mother Teresa, kalpana chawla, lata mangeshkar, sarojini naydu and many more.
1.14 “It is more important to have beauty in the equations of physics than 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-
Every equation of physics must be verified through experimentations. if it looks simple but does not comply with the experiment results it is of no use at all on the other hand it equation is complex but verified by experiment results then it is acceptable so experimental verification is more important than beauty of equation.
Equations in this chapter like
K.E = mV2
P.E = mgh
Both equations having energy as a function of different properties like speed and height depending upon different experiments done for calculating these equations. Hence if the equation is experimentally true along with simple and beautiful makes it more beautiful.